Improve logging

Apply improved logging from #116 to GravatarService
Run coveralls after build success

Related to #119
Merge pull request #132 from fernandoacorreia/coveralls

Run coveralls after build success
Revert "Run coveralls after build success"

This reverts commit a23cc0b379d0d4e956fbe4aec3819aaa97206e05.
Initial tests did not succeed.
Merge pull request #133 from fernandoacorreia/revert

Revert "Run coveralls after build success"
Merge pull request #128 from fernandoacorreia/GravatarLogger

Improve logging
Fixes #129 and #130
Merge pull request #135 from akkie/master

Fixes #129 and #130