commoncrypto initial backend
commoncrypto backend docs
simpler method of importing CommonCrypto backend into _ALL_BACKENDS
Merge branch 'master' into common-crypto-backend

* master:
  Use pytest.fixture for backends
  drop to >= 0.8 to make pypy happy
  change to anonymous enum
  require cffi >= 0.8.1
  remove extraneous spaces
  add hmac to commoncrypto binding
  bytes byte back
  add check to confirm we've loaded error strings
  Bind all the PEM errors
  Spelling!
  oops, bytes plz
  don't leak a context in the test
  add tests to the openssl backend to verify that we've registered
  Nonsense I think we need.
  This is a dep
  init the ssl library in the backend
  Actuall install a thing
  Try to run the spellchecker on travis
  Use a normal quote here, not sure where the smart quote came from
  Expose ERR_load_SSL_strings
add iOS to wordlist
support --backend as a pytest flag to limit to one backend for testing
pass posargs via tox so --backend can be used for tox envs
don't mutate _ALL_BACKENDS
better name for the variable
modify backend selection to allow multiple backends via comma delimiter
docs for explicit backend selection and document name attribute of backend
revert fixture decorator for now, switch to append. no more globals
Merge branch 'master' into common-crypto-backend

* master: (24 commits)
  Expose the innards of DH and DSA
  More bindings for asymmetric stuff
  Tell cffi these opaque types are pointers.
  rename variable to be less confusing and terrible
  Document when the common crypto bindings were added
  Expose a name needed for ECDHE -- the NIDs are always available
  Expose the nids for the various eliptical curve things. I don't understand what these mean.
  Specify the epub theme to fix the epub build on RTD.
  Added forgotten decl
  reversed
  Allow these to not be defined because lololol fedora/centos
  add conditional ERR_remove_thread_state. PyOpenSSL uses this
  Don't require sphinx spelling to be installed, for readthedocs benefit
  This is also a requirement
  oops
  Start binding some stuff for ECDHE in pyOpenSSL.
  check if openssl is installed via homebrew on osx. install if not
  Verify the tag len for GCM
  remove comment that's no longer needed
  Make just one call to ffi.cdef for most of the definitions
  ...
update docs, add name attribute to backend
stop using byte keys for no reason
rename a few things in an attempt to improve clarity
privatize hash_mapping
move HashMethods to top level
increase indent and note the value of the attribute in the docs
fix copy mistake in docs