Fix #74.
Remove console logging from the wrong place.
Relative, instead of absolute, imports in unit tests.
Use relative, instead of absolute, imports in system tests.
Rename system->integration tests.
Redundantly verify file length in updater.

You may argue that the redundancy is unnecessary (pun intended), but it
is there because redundancy means one safety check will work where
another fails. I introduced this redundant file length check because the
updater unit test is mocking the download functions, which means that
file length checks in the download functions are being bypassed.
Redundancy is a good thing for safety.
Fix a bug in updater unit test.
Much better organization of tests.
Even better organization of tests; remove evpy.

Require higher versions of PyCrypto.
Merge branch 'demo2' of https://github.com/zanefisher/tuf into demo2

Conflicts:
	tests/unit/test_updater.py
Merge unit test fix from @zanefisher; fix a unit test bug.
Review and update crypto comments in rsa_key.py
Replace relative with absolute imports for tests.
Continue self-review of PyCrypto changes to keystore.py
Merge branch 'demo2' of https://github.com/theupdateframework/tuf into demo2
Fix unit test failure in test_roledb.py

Ensure roledb is empty prior to running the test cases.  roledb.py may have been modified by other unit tests that did not properly clean up.
Fix test_keystore.py unit test failure

Ensure the keystore is empty prior to running the test cases.  The courtesy bug is spreading.
Fix #102.
Merge remote-tracking branch 'origin/demo2' into demo2
Fix test_util_test_tools.py test case failure

Clear the keystore before initializing the util_test_tools.py repository and again after every test case exits.