removed Activity and related classes

Now that the URL fragment (hash) specifies enough information
to restore each page (either through a direct link, or the
user of the browsers page history), we no longer need to
store navigation context in the server session.
add result value for test result for passed tests
unquote input and expected value strings for python submissions

This avoids the confusion that results by showing "xyz"
as the expected value, but xyz as the actual value.
avoid compiling EasySandbox library when trying to clean it up

If no C/C++ submissions are ever compiled/tested, then
the EasySandbox shared library will never be created.
However, the EasySandboxSharedLibrary singleton is guaranteed
to be accessed when the builder daemon shuts down, and
we want to avoid spuriously compiling the library at that point.
rather than unquoting input and expected, add quoting to actual output

This is done for Python only (although we should probably
generalize it to the other languages as well): if the
input is quoted (starts with ' or "), then we assume that
the expected output is a string, and add single or double
quotes as appropriate.