Allow to create rc service file

Summary:
Automate service.sls and /etc/rc.conf.d provisioning.

The mechanism is generic enough to be able to write other templates too.

Variables are replaced with:

• keys from _resources/templates/templates.yml
• values from the command line last arguments

The following special variables are replaced:

• %%path%% for current file (e.g. roles/foo/bar/files/bar.cfg)
• %%cwd%% for current directory (normally roles/foo/bar)

Usage: /path/to/utils/templates/create.py service <service name>

Test Plan:
Service of D3570 has been generated with:

$ cd roles/shellserver/bitlbee
$ ../../utils/templates/create.py service bitlbee

Reviewers: DorianWinty

Reviewed By: DorianWinty

Differential Revision: https://devcentral.nasqueron.org/D3571