fixed bug: crash on tapping on the background,  when dismissTapAnywhere and disableTapToDismiss  are all set to YES.
Merge branch 'master' of https://github.com/Jiequan/CMPopTipView
# background colour fix
Merge branch 'master' of https://github.com/Jiequan/CMPopTipView into Jiequan-master
Refactors dismiss by user handling to clean up; removes fade out background effect.