Bug 1085232: make profile-symbolicate work with Python < 2.7.6.

Python, series 2.7, has a bug in the regular expression module [1]
regarding regular expressions repetition, which was only fixed in the
version 2.7.6.

We abandon the URL regular expression validation method and consider
that any path starting with the "http" string is a valid URL.

[1] http://bugs.python.org/issue18647