Migrated build system to use alienfile + Alien::Build + Alien::Base
Changes for version v0.0.6_01 - 2015-01-18
Migrated build system to use Alien::Base. This allows the version of of GMP to always track the latest rather than using `gmp-5.0.4.tar.bz2` each time.
Using Alien::Base changes the functions `inc_dir()` and `lib_dir()` to methods `cflags()` and `libs()`.