New preferences setting for font size of log window

User can choose the font size
Value is clamped to 8 - 100
fixes issue #15
Merge branch 'luckyhacky-textsize'
Allow start/stop tinc by external intent. Bump version to 0.9.9.
Fixes #17.
Move getLogFontSize to activity instead of service.
It's GUI related anyway, and avoids a NullPointerException when the
service is not bound yet.
Bump to 0.9.10.
Fixes #24.
Fix NullPointerException when hosts subfolder is not readable.
Release 0.9.11.
Fixes #24.