Merge pull request #394 from tamcap/master

Cleaning up the error output of MainActivity.java
Decrease scan report watermark count to reduce memory usage
Don't log empty response if server returns HTTP 204 No Content
Allow nullable mGpsPosition so we don't need to track mGpsPositionTime separately
Separate Wi-Fi and cell report generation
Merge pull request #395 from cpeterso/cpeterso/refactor-reporter

Refactor reporter to reduce memory usage
Merge remote-tracking branch 'upstream/master'