Updated .gitignore, preparing for a new 1.6 build.

Signed-off-by: Ken 'Minalien' Murray <minalien@gmail.com>
Updated for Forge 859, ready for 1.6.2 consumption. Only BuildCraft power systems work at the moment.

Signed-off-by: Ken 'Minalien' Murray <minalien@gmail.com>