Version 1.2.0 is way too old in order to build the latest chromium (29) version,
so let's get it up to date (especially because no other package is referencing
ninja, so it should be non-critical).
The dependency on unzip is not needed here, because GitHub also provides
archives in tar.gz format.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
ninja is a build system written in C++ that just happens to use python
to build/install *itself*. It is not a "python package".
After this commit, ninja will be at pkgs.ninja instead of
pkgs.pythonPackages.ninja.
