Remove MongoDB 2.4 from the build matrix and use the latest stable driver by default.

Add explicit jobs to test MongoDB 2.4, driver 1.1.0 (oldest supported version), and the latest unstable driver version. Lastly, restrict PHP 5.4 and 5.5 to a single job each.

Previously, the values were set to an empty value, which causes exceptions within the driver.

The return type documentation should have been updated when the typMap option was introduced in PHPLIB-164.

This should have been updated in PHPLIB-164.

The return type documentation should have been updated when the typMap option was introduced in PHPLIB-133.