update docs #124

Usage and options documentation up to date, based on http://docopt.org.
update docs #124

Command descriptions moved to README.md.
Update `cache` command docs, based on docopt.org.

Related to issue #124.
Update `new` command docs, based on docopt.org.

Related to issue #124.
Update `reset` command docs, based on docopt.org.

Related to issue #124.
Update `start` command docs, based on docopt.org.

Related to issue #124.
Update `uninstall` command docs, based on docopt.org.

Related to issue #124.
Update `install` command docs, based on docopt.org.

Related to issue #124.
Merge pull request #127 from gnclmorais/master

Update docs #124