Add ECC arithmetic primitives

This includes point addition, doubling and multiplication.
Add ECDSA signature generation
Add ECDSA signing and verification
Add ECDSA QuickCheck tests

This includes:
 - Arbitrary message with fixed prime curve.
 - Arbitrary message with fixed binary curve.
 - Fixed message with arbitrary curve.
Add benchmarks for secp160r1 and sect163k1
Add KAT tests for ECDSA
Update documentation
Merge remote-tracking branch 'upstream'
Remove references to untracked ECC tests
Merge pull request #9 from jdnavarro/master

ECDSA support