Add new tmux statusline prototype.

tmux.conf
	-Comment out existing `statusline` configuration.
	-Add new, work-in-progress statusline.

.gitmodules, vim/bundle/tmux-syntax
	-Add `vim` syntax-highlighting plugin for `tmux` config files.
Add more statusline config; battery_level.py.

tmux/battery_level.py
	-Add a script to output the computer's battery level and status.
Complete battery_level.py.

tmux/battery_level.py
	-Replace `battery_level()` with `battery_info()`, add
	`file_contents()` (modeled after the similar script
	`shell_scripts/battery_warningd.py`).
	-Add a Unicode energy symbol to the output battery-info whenever
	the battery's charging.
Add network information to the tmux statusline.

tmux.conf
	-Remove commented-out configuration statements for the old
	statusline.
	-Reformat new statusline statements such that they adhere to a
	maximum line-length of 79 characters.

tmux/network.sh
	-Add script to print the network name and signal strength, for
	use in the statusline.
Merge branch 'feature/tmux_statusline' into develop

tmux.conf, tmux(battery.py, network.sh)
	-Add a new `tmux` statusline, with a designated `tmux/`
	directory to contain any component scripts.