Added fade to card drag items

[REVIEW]
Added a white mask to cards that are being dragged.

Preview: http://webmup.com/1we4W/
Merge pull request #450 from poixen/ghostcards

Added fade to card drag items
Add community resource links to README

ref #452
Permit linux/clang/qt5 build to fail
Merge remote-tracking branch 'upstream/master' into servatrice_trustedsources