when user try to update a problem the fieldset and legend solution for that
problem is lost because legend and fieldset are not added in the markdownToXml.
So added new markups where fieldset is to be added and used ```>><<``` markup for
legend.

AC-103

Also, I replaced a number of tearDown methods with addCleanup instead.
And also remove some unneeded patch.stopall() calls.

TNL-1677

Per @sarina:
> `build_problem` is called in `_make_problem`, which other tests call
> in this class. A failure here will arise in other tests. This test is
> unnecessary.

TNL-1459

TNL-1419

It looks like one version of the class was first added [1] and then a
few days later, another was written [2]. The newer declaration appeared
lower in the file, allowing it to hide the other.

This removes the first, hidden declaration.

[1] commit 7aa493ec
    Date:   Fri Mar 1 10:36:20 2013 -0500
[2] commit f62dad2f
    Date:   Tue Mar 5 16:31:02 2013 -0500

This reverts commit 66b949b7.

This reverts commit 66b949b7.

* Added tests for `problem_types` CapaDescriptor property
* Improved indentation in tests
* Improved validation messages

TNL-952

for visual indent

for hanging indent

does not distinguish itself from next logical line

visual indentation

indentation of opening bracket's line