Added BlackBerry devices, HTC phones and Samsung tablets.
Merge pull request #25 from miguelsousa/more_devices

Added BlackBerry devices, HTC phones and Samsung tablets.
Add seperate function for calculate dpi
Automatic calculate ppi from json
Related to #11
Remove some PPI for auto calculate by script
Improve codding readibility
Related to #27
Merge pull request #27 from AliMD/auto-calc-json

Auto calculate ppi from json
added MacBook Pro Hi-Res (2010)

Before Retina: http://support.apple.com/kb/sp582
Update screens.json
Added BlackBerry 10 devices

BlackBerry 10 devices are ```"dppx":2``` as @LeaVerou said in #25. And
I added Q series (Q10 and 5)
Merge pull request #34 from jorgecasar/gh-pages

Updated BlackBerry 10 devices
Merge pull request #29 from fibric/patch-1

added MacBook Pro