jrunscript bootstrap.js fails in java 8

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Reiterating the issue from https://github.com/imagej/imagej-omero/issues/58, which is still happening in a fresh docker (via Travis) with oraclejdk8:

```
$ curl -O http://update.imagej.net/bootstrap.js
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 10016 100 10016 0 0 39010 0 --:--:-- --:--:-- --:--:-- 315k

The command "curl -O http://update.imagej.net/bootstrap.js" exited with 0.
$ jrunscript bootstrap.js update-force-pristine
adding the Fiji update site

loading remote updater

running remote updater

java.lang.IllegalArgumentException: argument type mismatch
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at java.lang.invoke.MethodHandleImpl$BindCaller$T/918312414.invoke_V(MethodHandleImpl.java:941)
at jdk.nashorn.internal.scripts.Script$bootstrap.runScript(bootstrap.js:329)
at jdk.nashorn.internal.runtime.ScriptFunctionData.invoke(ScriptFunctionData.java:535)
at jdk.nashorn.internal.runtime.ScriptFunction.invoke(ScriptFunction.java:209)
at jdk.nashorn.internal.runtime.ScriptRuntime.apply(ScriptRuntime.java:378)
at jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:568)
at jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:525)
at jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:521)
at jdk.nashorn.api.scripting.NashornScriptEngine.eval(NashornScriptEngine.java:187)
at javax.script.AbstractScriptEngine.eval(AbstractScriptEngine.java:249)
at com.sun.tools.script.shell.Main.evaluateReader(Main.java:332)
at com.sun.tools.script.shell.Main.evaluateStream(Main.java:368)
at com.sun.tools.script.shell.Main.processSource(Main.java:285)
at com.sun.tools.script.shell.Main.access$100(Main.java:37)
at com.sun.tools.script.shell.Main$2.run(Main.java:200)
at com.sun.tools.script.shell.Main.main(Main.java:48)
```

Start by downloading bootstrap.js and reproducing the failure with `jrunscript bootstrap.js update-force-pristine` on Oracle JDK 8, then inspect the code around bootstrap.js:329 and the remote updater invocation. Confirm the fix by rerunning the same command in a fresh Java 8 environment without the argument type mismatch.

Written by the indexing model from the issue text.