Packages for gcc and its dependencies.
Working GCC package.
Change to faster gcc mirror that allows spidering.
Improved website scraping.
URL parsing improvements
'spack urls' debugging command, more consistent URL extrapolation.

- spack urls inspects all URLs in packages, prints out colors to show how they are parased.
- URL extrapolation test added.
- Extrapolation is more consistent now.
- Extrapolation handles more complex URLs.
- More test cases for extrapolation.
Python 2.6 fix for Mac OS
Shorter help strings.
Merge branch 'features/gcc' into develop

Conflicts:
	lib/spack/spack/package.py