Updated the signing algorithm for the profile pics to hmac.
Only signing/exposing the large picture if the current user is requesting it.
Returning updated principal object in the REST crop apis.
Removed cairo as dependency.
Changed if (foo) { data.foo = foo} to data.foo = foo || undefined
Fixed typo in comments.
Merge pull request #308 from simong/pictureimprovements

Profile picture fixes
Added graphicsMagic as a dependency to the Travis CI build.
Updated .travis.yml with the correct graphicsmagick package.
Travis CI's version of git doesn't support --single-branch. Full clone of the 3akai-ux repo is required.
Added Travis.CI build icon, and GraphicsMagick as a dependency.
Added Email list & IRC to the Travis CI build notifications.
Merge branch 'master' into activity-poc-agg2

Conflicts:
	node_modules/oae-principals/lib/api.picture.js