python: make all objects hashable

This commit removes __cmp__() from all classes (BaseThread and
BaseFrame). This has the consequence that they inherit the default
__cmp__ and __hash__ making all objects hashable.

Instead of __cmp__(), method equals() is provided that decides
attribute-wise equality. It is currently only used in tests.

Closes #121.

Signed-off-by: Martin Milata <mmilata@redhat.com>
Merge pull request #123 from abrt/gh121-python-hash

python: make all objects hashable

This commit removes __cmp__() from all classes (BaseThread and
BaseFrame). This has the consequence that they inherit the default
__cmp__ and __hash__ making all objects hashable.

Instead of __cmp__(), method equals() i