Fixes incorrect parametrization of new log type

- the new log type oc_team_comment wrongly contained an icon name (used only by GC parser)
Fixes issue WRT to non-unique log type icon name
Update to RxJava 0.17.0-RC2
Fix failing tests

Fix failing tests due to changes introduced in
63b7d6b0454cd8ac4bbcbfe82f589f64581c82d7.
fix #3618: hint & log images are improperly displayed
refactoring: makes unsubscribing from image loading easier

This is related to #3618.
Ignore lint warning on missing Polish quantities

We have warnings about the Polish translations missing the
"many" quantity. We should ignore them at this stage until
we find a way to introduce them in crowdin.
refactoring: replace Handler by RxJava in send2cgeo registration
crowdin: New translations
Merge pull request #3620 from rsudev/crowdin_translations

crowdin: New translations
fix #3610: geocode search is case sensitive
refactoring: factor out common code in preferences
refactoring: replace Handler by RxJava in credentials checks
refactoring: properly type login result
Update changelog for release
Merge branch 'release' into upstream
Use explicit locale in upper case conversion

This silences lint, even though a geocode would work the same in any locale.
Remove unused string resource
Fixes #3608, TB details empty

- moved url null check to beginning of image fetch.