Add link to Google+ page to README
Add contribution guidelines
Slightly improve contribution guidelines
Fix website URL in README
Make Web API use HTTPS by default
Strip number suffixes from join date in SteamId

Closes koraktor/steam-condenser#215
Update powermock dependencies to 1.5.1
Update commons-compress dependency to 1.5
Update httpclient dependency to 4.2.5
Version bump to 1.3.5
Merge branch '1.3-stable'