Merge pull request #22 from limeyd/master

Add optional window name when loading windows
Fix typo
Bump version to 0.7.3
Enable load commands to accept file paths in addition to layout names

Resolves issue #20. Additionally, load_session now has an optional
second argument to set the default session name. And error output from
both load commands is now printed to STDERR and give a return code of 1
on error.
Bump version to 0.8.0
Fix issue #23 - Some consoles don't seem to support C-l
Bump version to 0.8.1
Enable passing custom arguments to tmux

Custom arguments can now be passed to tmux by setting the
TMUXIFIER_TMUX_OPTS environment variable.
Bump version to 0.9.0