Remove duplicate lists function from Eloquent Collection

Signed-off-by: Dries Vints <dries.vints@gmail.com>
set grammar table prefix when prefix is set on connection.
Merge pull request #1535 from driesvints/feature/lists-function-on-collection-class

Add lists method to Collection class
Add implode method to Collection class and Query Builder

This makes it easy to glue values or column or key inside a collection or a DB result set together.

Signed-off-by: Dries Vints <dries.vints@gmail.com>
Cleaning up some code.