BUG: Bug fix for Issue #5315

Added new logic to the fortran compiler version check to handle cases where
gcc is built with "--with-pkgversion=*some_string*, where *some_string*
contains numbers that might be incorrectly interpreted as a gcc version.

This includes some additional tests. All tests run successfully on Linux
Python version 2.7.8 and 3.4.2.
Should finish up the documentation with
```
Parameters
---------------
s : str
    String that is assumed to follow a '('.

Returns
----------
stripped : str
    The input string stripped of the parenthetical part that
    began with the assumed '(' preceding the input string.

"""
```
No reason not to follow the docstring standard here.