Merge pull request #5 from RaetProtocol/master

Added support for OS X
Add encode module with simple encoding functions
Add high level public key management
Correct calls to nm routines
Add high level wrapper for secretbox
Move BaseKey into utils
Add high level for key signing
fix calling order
make secretbox inherit BaseKey
add libnacl.encode import
Set the vk key hex routine correctly
correct return tuple
enable nm tests, it works now
rename raw tests to well, raw
Add high level tests for public key encryption
Add high level secret tests
Add high level signing capabilities
python3 compat
add signature method
Add tests for Signer.signature