Merge pull request #71 from reaperhulk/cryptrec-openssl-loader

add cryptrec and openssl test vector loaders + tests
lower ciphername, add api supports, improved assertion message

* supports method added to api to check if a ciphername is available.
  This will be used with skipif (and probably elsewhere)
* ciphername lowered. OpenSSL frequently supports aliases for various
  casing, but reliably supports all lowercase.
  (e.g. camellia-128-cbc, vs Camellia-128-CBC)
* When a cipher is not found an error will now be raised telling you
  what string cipher it couldn't find. This should probably become a
  real error like CipherNotFoundError.
show skipped test reasons via tox
Camellia block cipher support

* Tests for CBC, OFB, CFB, and ECB
* Tests will be automatically skipped if camellia support is not present
  in your OpenSSL library (e.g. OS X 10.8 with default OpenSSL)
* Test for unsupported cipher in create_block_cipher_context
* Docs for the cipher