Implement a simple tokenlib module.

The tokenlib module handles creation and parsing of tokens based on a HMAC
verification
Server: generate call tokens
Depend on the server info to generate host/protocol
[Tokenlib] Test we're returning hexa values
[Tokenlib] slice to 32 bits instead of 32 bytes
[Tokenlib] switch to base64 url safe encoding
[Tokenlib] Encapsulate encode and decode into a TokenManager
Add a .jshintrc file and fix a few related errors
Merge pull request #3 from mozilla/tokenlib

Tokenlib