added share block to right sidebar when reviewing an exam
Merge branch 'master' of https://github.com/Stanford-Online/class2go into giulio-share-results
more share block code
added working twitter sharing
removed excess verbage in Raw Score label
added facebook share and google plus share
fixing redundancy pointed out by @dcadams
fixed twitter tab not working - closes #2248 & closes #2249
Merge pull request #2363 from Stanford-Online/giulio-share-results

Share results of assignments/quizzes/exams on twitter (closes #2248 & closes #2249)