Fixed panic when callerName doesn't have package

The callerName can be in two formats:

    com/remogatto/prettytest.(*testSuite).Should_be_cool
    (*testSuite).Should_be_cool

Currently only the first case was handled and the second caused a panic.
This commit allows support for both.
Simplified BDDFormatter's splitString a bit
Merge pull request #14 from pranavraja/master

Fixed panic when suiteInfo.callerName does not contain the package