Initial versions of Qt and some dependencies.
gnutls, nettle, wget, dbus
Updates for Qt dependencies
Print out fetch, build, and total time for builds.
Add patch function to Package, so that packages can define custom patch functions.
spack env command

spack env allows regular commands to be run with a spack build environment.
It also displays the spack build environment for a package.
Clearer code in filter_file.
Qt4 builds successfully with proper RPATHs.
Fix up bzip2 install
Merge branch 'features/qt' into develop