Coding style fixes

Based on http://laravel.com/docs/4.2/contributions#coding-style
Small improvements
Merge pull request #9 from billmn/patch-2

Code improvements
Fixed error founded by marsd
Laravel 5 support
Merge pull request #11 from alextyrey/patch-1

Laravel 5 support
Update README.md
Update README.md
Postgres compatibility
Different queries for each database driver
Update README.md to if => case
Merge pull request #14 from nicolaslopezj/postgres

Postgres
sql injection security
Merge branch 'master' of https://github.com/nicolaslopezj/searchable

Conflicts:
	src/Nicolaslopezj/Searchable/SearchableTrait.php
No require DB;
change == 'pgsql' to != 'mysql'
quoted bindings
change to case, added group by
Fixed quotes. back to normal group by
table columns for sqlsrv