Fix for issue 57 (Remove  prefix from angular-datatables service names)

This is a fix for [Issue 57](https://github.com/l-lin/angular-datatables/issues/57) - Remove prefix from angular-datatables service names. From the [Angular API docs](https://docs.angularjs.org/api):

>Angular Namespaces $ and $$ To prevent accidental name collisions with your code, Angular prefixes names of public objects with $ and names of private objects with $$. Please do not use the $ or $$ prefix in your code.

The following name changes were made to the offending services:

- $DTBootstrapTableTools => DTBootstrapTableTools 
- $DTBootstrapColVis => DTBootstrapColVis
- $DTBootstrap => DTBootstrap
- $DTDefaultOptions => DTDefaultOptions
- $DTPropertyUtil => DTPropertyUtil