Memory improvement at the cost of less portability

You may disagree on this pull request because it removes the regexp delimiter escaping need by using a regexp delimiter (#) that is not used today in user agents or properties. But as a consequence, it is required that no UA or properties using the # sign in the future are added to mobile-detect regexes.

Else use this patch to save cpu time and memory.

Test results on a desktop browser ($md->isMobile() test)

![image](https://cloud.githubusercontent.com/assets/1324566/3894854/ca28c7a4-2248-11e4-819b-237823c26c18.png)