Reporter/HttpUtil cleanup items for easier testing/debugging

Reporter/HttpUtil cleanup
While debugging MLSLocationGetter I ran into a few cleanup issues
- wasSent() doesn't seem to serve a purpose, removed
- changed some Log.e(...) to be more concise as the code I was debugging
was spamming the log when throwing exceptions
- added errorMLSResponse on MLSLocationGetter to clear the state after
an error
- In Reporter.java, I added a check for zero wifi and cell count, it is
hard to repro, it happens when I modify the code for load testing (as I
typically do), but it helps prevent false errors when testing at the
very least.
After a failure, the ObservationPoint will hold an instance of mMLSLocationGetter, which is not re-usable (it is an asynctask), so it should be set to null.