Switch to DeviceDetector 2.X

* Switched to DeviceDetector 2.X
* Do detection only once (in tracker/settings). There is no need doing device type detection in DeviceDetection plugin as all those detections are already done before (Doing them twice slows down tracking)
* Introduce new DeviceDetectorCache to use an optimal caching for DeviceDetector (File Cache + Static Caching)
* Speed up detection for bulk requests (thx to @cbonte)
* Use special parsers where only those are needed (e.g. check for bots or mobile os)
@tsteur is working on this in this branch: https://github.com/piwik/piwik/tree/report_and_dimension_refactoring 
In this branch. all reports and custom columns will be put in their own plugins after this huge refactor. 

After Thomas merges master in his branch, then the code regarding DevicesDetection should be all (or almost all) in the plugin itself.