move PageStack to client.model package (where it was supposed to be)
get rid of comment template for overriding methods
added ProblemSubmissionHistory model object

This will be the basis for refactoring UserProblemSubmissionsPage
into separate views (all of which visualize the
ProblemSubmissionHistory object.)
factored submission history slider view out of user prob submission page
factored problem text view out of UserProblemSubmissionsPage
support parallel execution in BatchMain (multicore FTW!)
hmm...multiple threads seem to produce unpredictable results

Need to investigate further.  For now, just use a single
worker thread.
added RepoProblemRating model class

This will allow repository users to rate repository exercises.
fix name of db table for RepoProblemRating class
add RepoProblemRating table to list of tables for repo db
fix classpath
updated to latest AceGWT
added shared field to Problem class (and IProblem interface)

This keeps track of whether the Problem has been shared to the
exercise repository.
keep track of which exercises have been shared

UI still needs some work.
use the green checkmark image to mark shared exercises
adjust column widths in CourseAdminProblemListView
reload problems when a problem is shared (so shared flag is updated)
remove spurious carriage returns
Merge branch 'master' of github.com:cloudcoderdotorg/CloudCoder

Conflicts:
	CloudCoder/src/edu/ycp/cs/dh/acegwt/client/ace/AceEditor.java
start integrating EasySandbox, for sandboxing C/C++ programs