Implement gcd and bitLength methods
fix for nodejs v0.10.1
Fix incompatibilty with recent V8 versions.
Merge pull request #13 from jess-sheneberger/master

fix for v0.10.1
Merge pull request #12 from devongovett/master

Added gcd and bitLength methods
Bump version to 0.6.0.
Add more Node versions for testing.
Merge branch 'master' of https://github.com/justmoon/node-bignum