Merge branch 'develop' of https://github.com/theupdateframework/tuf into develop
Merge and resolve conflicts
Commence configurable crypto changes

Refactored the majority of affected modules.  Added optimized version of the reference implementation of ed25519.
Continue configurable crypto design changes

Add new schema to formats.py and simplify input validation in keys.py
Add updated schema description of new schema in formats.py
Support adding any key type in keydb.py

Fix docstrings for whitespace consistency.
Modify updater.py to support multiple key types
Modify signerlib.py to support multiple key types

Fix docstrings for whitespace consistency.
Continue configurable crypto changes: add keys.py doctest
Fix import, doctests, and function parameters in keys.py
Add missing doctests to keys.py and pycrypto_keys.py
Modify behavior of configurable crypto and update conf.py

Add missing doctest and minor edits.
Fix docstring whitespace in formats.py
Update all unit tests affected by configurable crypto

Add separate 'tuf.conf.py' options for key types.
Add new keytype schema in formats.py
Add test_keys.py and update keys.py
Move test cases to test_pycrypto_keys.py
Update object schema names in formats.py

Modify the object name of a schema so that FormatError error messages are clearer about which schema is expected.
Update test cases moved over to test_pycrypto_keys.py

test cases updated with configurable crypto changes.
Add remaining test cases in test_pycrypto_keys.py