forge.pkcs1: Implementation of RSA-OAEP using Forge.

nodejs-pkcs1.js: Test the implementation using RSA's test vectors.
pkcs1: Replace xorString using forge.util.xorBytes

Removes assertions verifying that the two strings are the same length, but is
otherwise equivalent.
nodejs-pkcs1.js: Add test for zero byte message; Fix lint warnings.
Add better support for different RSA signature/encryption schemes.
Merge branch 'master' of git://github.com/evanj/forge into evanj-master
Enable use of RSAES-OAEP through standard API.

- Alter pkcs1 RSAES-OAEP to only do encoding/decoding to separate
  concerns and bring it inline with other schemes.
- Update tests to use both lower level and higher level APIs for
  RSA encryption + RSAES-OAEP.
- Make pkcs1 module a dependency of rsa module.