Remove unused class properties in WriteConcern
PHP-1173: Use string "majority" for WriteConcern::MAJORITY

The purpose is two-fold: abstract libmongo'c constant (defined as -3) from our users and ensure the string "majority" is sets the struct's "w" field properly even if our constant is not used.
Merge pull request #20
Clean up hex_dump() source and add citation
Use preg_replace() for generating collection name from test file

This builds on what already existed in the current driver and adds the ".skip" removal. It also replaces hyphens with underscores to ensure that the collection is easy to access from the shell.
Use "phongo_test" as default test database
Use require_once in skip test includes
Use Faker to create user data fixtures
Functional tests for sorted queries