Switched hash functions from PyCrypto to hashlib.

There's a few advantages to this:

1) It's probably fast, OpenSSL, which typically backs hashlib, receives far
   more attention for optimizaitons than PyCrypto.
2) It's the first step to supporting PyPy, where PyCrypto doesn't run.
Remove unused function
Switch from using PyCrypto's Random to using os.urandom.

There's several reasons for this change:

1) It's faster for reads up to 1024 bytes (nearly 10x faster for 16 byte reads)
2) It receives considerably more security review since it's in the kernel.
3) It's yet another step towards running on PyPy.
4) Using userspace CSPRNGs is considered something of an anti-pattern. See:
   http://sockpuppet.org/blog/2014/02/25/safely-generate-random-numbers/
   http://webcache.googleusercontent.com/search?q=cache:2nTvpCgKZXIJ:www.2uo.de/myths-about-urandom/+&cd=3&hl=en&ct=clnk&gl=us
The ecdsa module already defaults to using urandom.
Use deterministic signatures for ECDSA keys.

This is now considered the preffered approach across the board for ECDSA. This
is because with the traditional, random "k" parameter for ECDSA, any entropy
problems at all, even a single bit, about "k", results in a complete compromise
(see https://en.wikipedia.org/wiki/ECDSA#Security). The deterministic algorithm
doesn't have this downside.
Merge remote-tracking branch 'alex/hashlib-hashes' into 295-int
Errything uses intersphinx to Python
Changelog, closes #295
Merge branch '295-int'
Derp
Merge pull request #296 from alex/remove-unused

Remove unused function
Merge branch 'master' into use-urandom

Conflicts:
	paramiko/dsskey.py
	paramiko/ecdsakey.py
	paramiko/hostkeys.py
	paramiko/kex_gex.py
	paramiko/kex_group1.py
	paramiko/pkey.py
	paramiko/primes.py
	paramiko/rsakey.py
	tests/test_pkey.py
Merge branch 'master' into ecdsa-deterministic

Conflicts:
	paramiko/ecdsakey.py
Changelog, closes #297
Merge branch 'master' into ecdsa-deterministic

Conflicts:
	paramiko/ecdsakey.py
Changelog, closes #299