Listing big activations may result in error with Cosmos

At times following error is seen when listing activations (specially with limit=0) when individual activation sizes are large. This only seen on deployments using Cosmos

```
[2018-10-05T06:47:46.373Z] [INFO] [#tid_tvEBT8zB92oWDoULDmpZNq3Iqi8CUOGQ] GET /api/v1/namespaces/_/activations docs=true&limit=0&since=1538655040002&skip=0
[2018-10-05T06:47:46.373Z] [INFO] [#tid_tvEBT8zB92oWDoULDmpZNq3Iqi8CUOGQ] [BasicAuthenticationDirective] authenticate: xxxx
[2018-10-05T06:47:46.373Z] [INFO] [#tid_tvEBT8zB92oWDoULDmpZNq3Iqi8CUOGQ] [Identity] [GET] serving from cache: CacheKey(xxxx) [marker:database_cacheHit_count:1]
[2018-10-05T06:47:46.373Z] [INFO] [#tid_tvEBT8zB92oWDoULDmpZNq3Iqi8CUOGQ] [CosmosDBArtifactStore] [QUERY] 'activations' searching 'whisks.v2.1.0/activations' [marker:database_queryView_start:1]
[2018-10-05T06:47:46.522Z] [ERROR] [#tid_tvEBT8zB92oWDoULDmpZNq3Iqi8CUOGQ] [StoreUtils] [QUERY] 'activations' internal error, failure: 'Response entity too large: HttpObjectAggregator$AggregatedFullHttpResponse(decodeResult: success, version: HTTP/1.1, content: CompositeByteBuf(ridx: 0, widx: 2095923, cap: 2095923, components=256))
HTTP/1.1 200 Ok
Cache-Control: no-store, no-cache
Pragma: no-cache
Content-Type: application/json
Server: Microsoft-HTTPAPI/2.0
Strict-Transport-Security: max-age=31536000
x-ms-last-state-change-utc: Wed, 03 Oct 2018 21:23:07.609 GMT
x-ms-continuation: +RID:wLQoAKn2hi8sEwAAAAAAAA==#RT:1#TRC:100#RTD:rknCdmPyEeSA#FPC:AgEAAAB2AAIG4J3BA3ECmANhgLQAAPAAwEoHCwcRAAADJAQFANgCAMA/ACQDOgCA/+H8YQBBAPDxFQDA/wP+Azjw4f0PcQBw/hVAD/wPwIcD/PkeALMAAPgDAH8gogUAhw8AUQHgAdEA8OBSAoADmAAcg/QGfAAA/n8fHgA=
lsn: 10633
x-ms-item-count: 100
x-ms-schemaversion: 1.6
x-ms-alt-content-path: dbs/openwhisk/colls/activations
x-ms-xp-role: 1
x-ms-global-Committed-lsn: 10632
x-ms-number-of-read-regions: 0
x-ms-transport-request-id: 1424
x-ms-cosmos-llsn: 10633
x-ms-session-token: 0:10633
x-ms-request-charge: 400.09
x-ms-serviceversion: version=2.1.0.0
x-ms-gatewayversion: version=2.1.0.0
Date: Fri, 05 Oct 2018 06:47:45 GMT' [marker:database_queryView_error:150:149]
[2018-10-05T06:47:46.522Z] [ERROR] [#tid_tvEBT8zB92oWDoULDmpZNq3Iqi8CUOGQ] [ActivationsApi] [LIST] entity failed: Response entity too large: HttpObjectAggregator$AggregatedFullHttpResponse(decodeResult: success, version: HTTP/1.1, content: CompositeByteBuf(ridx: 0, widx: 2095923, cap: 2095923, components=256))
HTTP/1.1 200 Ok
Cache-Control: no-store, no-cache
Pragma: no-cache
Content-Type: application/json
Server: Microsoft-HTTPAPI/2.0
Strict-Transport-Security: max-age=31536000
x-ms-last-state-change-utc: Wed, 03 Oct 2018 21:23:07.609 GMT
x-ms-continuation: +RID:wLQoAKn2hi8sEwAAAAAAAA==#RT:1#TRC:100#RTD:rknCdmPyEeSA#FPC:AgEAAAB2AAIG4J3BA3ECmANhgLQAAPAAwEoHCwcRAAADJAQFANgCAMA/ACQDOgCA/+H8YQBBAPDxFQDA/wP+Azjw4f0PcQBw/hVAD/wPwIcD/PkeALMAAPgDAH8gogUAhw8AUQHgAdEA8OBSAoADmAAcg/QGfAAA/n8fHgA=
x-ms-resource-quota: documentSize=10240;documentsSize=10485760;documentsCount=-1;collectionSize=10485760;
x-ms-resource-usage: documentSize=101;documentsSize=100630;documentsCount=10627;collectionSize=103432;
lsn: 10633
x-ms-item-count: 100
x-ms-schemaversion: 1.6
x-ms-alt-content-path: dbs/openwhisk/colls/activations
x-ms-xp-role: 1
x-ms-global-Committed-lsn: 10632
x-ms-number-of-read-regions: 0
x-ms-transport-request-id: 1424
x-ms-cosmos-llsn: 10633
x-ms-session-token: 0:10633
x-ms-request-charge: 400.09
x-ms-serviceversion: version=2.1.0.0
x-ms-gatewayversion: version=2.1.0.0
Date: Fri, 05 Oct 2018 06:47:45 GMT
[2018-10-05T06:47:46.522Z] [INFO] [#tid_tvEBT8zB92oWDoULDmpZNq3Iqi8CUOGQ] [BasicHttpService] [marker:http_get.500_count:150:150]
```