requirements.txt: Added flags for PIL.
Update installation-makahiki-unix.rst

Fixed capitalization of "Install pip" section header for consistency.
doc/installation-makahiki-unix.rst: Fixed command that needed to be run with sudo.
Merge branch 'master' of http://github.com/jtakayama/makahiki
Merge branch 'master' of http://github.com/jtakayama/makahiki into second-vm-testing