Improvements to DevicesDetection plugin

* added/enhanced/fixed quite many detection rules for different devices
* added/improved detection of some browsers/os
* added "Device detection" tool to admin, so every user (admin) can check if a useragent is correctly parsed (including the possibility to show a list of all brands/browsers/os/device-types known to piwik)
* improved detection code in useragentparserenhanced
* added new device type 'smart display'
* added possibility to translate device types

Could anyone please have a closer look before merging? Thx.