Updated build tools version

Merge pull request jakob-grabner#42 from sensen/fix-writing

Fix writing in README.md

Merge branch 'master' of https://github.com/jakob-grabner/CircleView

Merge branch 'YvesDelcoigne-custom-typeface'

Merge branch 'master' of https://github.com/jakob-grabner/CircleView

Merge pull request jakob-grabner#22 from YvesDelcoigne/patch-1

Update AndroidManifest.xml: removed android:allowBackup="true"

Fixed jakob-grabner#19: Margin of 0 was not possible.

Update README.md

Fix jakob-grabner#12: Show text in spinning mode.

Fix jakob-grabner#11 text color white (which is -1) was treated as "no color" constant. Use setAutoTextColor(boolean) not to define auto color behaviour.
Added: Custom start angle, use setStartAngle(int)
Added: Annotations for value ranges.

Update README.md