Changes to git ignores

- Excluded entire vendor directory as composer can take care of these dependencies
- Removed user specific exclusions which are better placed in ~/.gitignore
- Removed composer lock file from exclusions
Removed vendor directory as managed by composer
Added composer lockfile
Allow Pico to run from subdirectories

Borrowed the htaccess rewrite rules from Symfony 2.

Pico's urls were broken if installed in a subdir
e.g. http://localhost/~gaz/Pico/sub/page