Python to 2.7.12 with openssl support & readline to 6.3 to fix the undefined symbol: rl_signal_event_hook problem

I'm bad with my reverts because I'm reverting through github since I'm on my virgin chromebook

Reverting back the changes I was trying for pull 178 in the master repo

Recently formattet my chromebook pixel and wanted to try everyone's change of install.sh so I've merged pull https://github.com/skycocker/chromebrew/pull/176 into mine to try it.

add packages/yasm.rb

add fish package

Libevent and tmux fixes

Fix url in installation to avoid 301 redirects

Merge branch 'libevent-and-tmux-fixes' of github.com:minektur/chromebrew into libevent-and-tmux-fixes

3 changes to get tmux to work:
update tmux to latest release

remove openssl dependency for libevent (partly because openssl forumla
on chromebrew is broken right now, partly because we dont need it.)

change command line options for wget in crew script:
man page says -N is incompatible with -O (and wget complains every run)
--content-disposition not needed since we specify -O and big files on
github (which are backed by aws) can not be retrieved with this flag,
probably because AWS doesn't support HEAD requests for those files