NpmMetaAnalyzer Request Failure

### Current Behavior:
I have continious Dependency-Track logs going back to 14 May 2019 (when I was running v3.4.1).

Starting one hour after upgrade from 3.4.1 to 3.5.0 on 7 June, the logs show (for me) 748 occurrences of:

```
2019-06-07 11:39:24,654 [] ERROR [org.dependencytrack.tasks.repositories.NpmMetaAnalyzer] Request failure
kong.unirest.UnirestException: java.net.SocketTimeoutException: Read timed out
```
There is no logging for NpmMetaAnalyzer before upgrade to 3.5.0 and no logging after upgrade that is not a Request failure ERROR.

The errors all seem to occur around the middle of the day (UTC), with sometimes just 2 or 3 per day and sometimes as many as 10.

### Steps to Reproduce:
Search logs for `NpmMetaAnalyzer]`

### Expected Behavior:
Log events for `NpmMetaAnalyzer` should not be associated with "Request failure" & `SocketTimeoutException`

### Environment:

- Dependency-Track Version: 3.6.0
- Distribution: [ Executable WAR ]
- BOM Format & Version: CycloneDX 1.1
- Database Server: [ PostgreSQL ]
- Browser: Firefox 69.0.2

### Additional Details:
From today's log (running DT 3.6.0):

```
2019-10-09 14:19:49,845 [] ERROR [org.dependencytrack.tasks.repositories.NpmMetaAnalyzer] Request failure
kong.unirest.UnirestException: java.net.SocketTimeoutException: Read timed out
at kong.unirest.apache.ApacheClient.request(ApacheClient.java:133)
at kong.unirest.BaseRequest.asJson(BaseRequest.java:213)
at org.dependencytrack.tasks.repositories.NpmMetaAnalyzer.analyze(NpmMetaAnalyzer.java:80)
at org.dependencytrack.tasks.repositories.RepositoryMetaAnalyzerTask.analyze(RepositoryMetaAnalyzerTask.java:87)
at org.dependencytrack.tasks.repositories.RepositoryMetaAnalyzerTask.inform(RepositoryMetaAnalyzerTask.java:70)
at alpine.event.framework.BaseEventService.lambda$publish$0(BaseEventService.java:97)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.net.SocketTimeoutException: Read timed out
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
at java.net.SocketInputStream.read(SocketInputStream.java:171)
at java.net.SocketInputStream.read(SocketInputStream.java:141)
at sun.security.ssl.InputRecord.readFully(InputRecord.java:465)
at sun.security.ssl.InputRecord.read(InputRecord.java:503)
at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:983)
at sun.security.ssl.SSLSocketImpl.readDataRecord(SSLSocketImpl.java:940)
at sun.security.ssl.AppInputStream.read(AppInputStream.java:105)
at org.apache.http.impl.io.SessionInputBufferImpl.streamRead(SessionInputBufferImpl.java:139)
at org.apache.http.impl.io.SessionInputBufferImpl.fillBuffer(SessionInputBufferImpl.java:155)
at org.apache.http.impl.io.SessionInputBufferImpl.readLine(SessionInputBufferImpl.java:284)
at org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:138)
at org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:56)
at org.apache.http.impl.io.AbstractMessageParser.parse(AbstractMessageParser.java:261)
at org.apache.http.impl.DefaultBHttpClientConnection.receiveResponseHeader(DefaultBHttpClientConnection.java:165)
at org.apache.http.impl.conn.CPoolProxy.receiveResponseHeader(CPoolProxy.java:157)
at org.apache.http.protocol.HttpRequestExecutor.doReceiveResponse(HttpRequestExecutor.java:272)
at org.apache.http.protocol.HttpRequestExecutor.execute(HttpRequestExecutor.java:124)
at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:272)
at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:186)
at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:89)
at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:110)
at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:185)
at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:83)
at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:108)
at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:56)
at kong.unirest.apache.ApacheClient.request(ApacheClient.java:125)
... 8 common frames omitted
```