Add url safe base64 option

v0.4.0

Bump version to 0.4.0

Bug fix

Fix Illegal invocation error when using aliased window.btoa or window.ato

Recompile Min and Bug Fixes

Fix syntax bugs
Recompile min file

Bug fix

Use native btoa and atob methods correctly if defined.

0.3.0

Remove polyfill in favor of module.exports.