ENH: Add DPI for Windows
ENH: Linux DPI support
FIX: OSX works
FIX: Fix for Python 2.6
FIX: Fix Py34 error
FIX: Unify subprocess calls
FIX: Fix examples test
FIX: Fix coveragerc
Merge pull request #567 from Eric89GXL/dpi

ENH: Query system for DPI