Made the role ansible-galaxy friendly.

The behaviour of the roles was not changed.

repository directory layout:
- Moved all the files from roles/monit to the repo root, in order to be
  follow ansible-galaxy standard.

defaults/main.yml:
- Move vars/main.yml to defaults/yml, since those values are defaults of
  the role to be costumized by the end user and not internal
  variable not to be changed.

variables:
- All variable names were prepended with "monit_" in order to create a
  "namespace" for this role, so these names won't collide with other
  roles' variables.

meta/main.yml:
- Added meta-description file, to be filled by the author.
Removed personal and license info from README.md.