[PR] Improved jinja handling for nginx, php, mysql

* [x] Use `salt['pillar.get']` in several places rather than passing context.
* [x] Provide a default value for nginx's `server_names_hash_max_size`.
* [x] Add jinja template for `my.cnf`.
* [x] Add jinja template for `php.ini`.
* [x] Setup variables for config in `my.cnf` and `php.ini`, provide defaults.