Add Contrib and Fix Powerline Colours

[trishume]

This PR was intended to just be about adding my own contrib layer, but because I messed up on some Git stuff, it includes other things as well (which I originally intended to be separate PRs).

Changes Included

• Adds a trishume contrib layer which adds LaTeX and smooth scrolling support (more goodies to come)
• Fixes the issue mentioned in Add support for Emacs 24.4 #21 about the powerline not having the right colours in inactive buffers
• The "custom" package added a section to init.el without asking. Maybe this should be in the repo so it doesn't keep inserting itself? Or is there some way to tell it to put this crap somewhere else (like .spacemacs)?

Also I'm back! Once XCode 6.1 was released on the app store I reinstalled emacs (24.4 now!) and am back to configuring it. Expect more PRs!

[syl20bnr]

Welcome back Tristan,
This is the first contribution layer for spacemacs!

You should not merge the master branch or upstream master branch (syl20bnr/spacemacs@master) into the PR branch (add-contrib). It breaks rebasing and lead to a non linear history in master.

If you want to get back the changes from upstream you should rebase your PR branch on top of the upstream branch like this: git pull --rebase upstream master (if you have called the remote repo syl20bnr/spacemacs upstream).

If you have any question about git feel free to ask them in this PR.

I've merge your changes by cherry-picking them with git cherry-pick commit-hash. I did not cherry picked the commit with the custom section stuff. Tell me if everything is fine in master and I'll close this PR. And you'll be safe to delete your add-contrib branch.

I created an issue to handle the custom section stuff, see #25

Thanks again for this first contribution layer :-)

[syl20bnr]

@trishume FYI here is what I did:

• fetch the PR commits into branch add-contrib-trishume git fetch origin pull/24/head:add-contrib-trishume
• cherry-pick a3e037b f14a82d and 41a0f08 into master
• interactively rebased them to squash them in only one commit git rebase -i HEAD~4
• I could have cherry-picked b08406d but applied it by hand instead, my mistake sorry for this (I thought it would require a merge otherwise). The result is the same though.

[trishume]

I commented on this before but it seems to have gotten lost.

This is great, thanks for fixing my git screw-up. I had realized when I went to create a PR that I shouldn't have done that merge.

You can close this now.

[syl20bnr]

no prob!