added that signing is done with the xcode default settings
Fixes to run Xcode build w/o resigning the app directory contents.

- dependency on infoplistModify is added to xcodebuild only when
infoplist settings are defined.
- ProvisioningCleanup now checks if directory exists before removing it.
fixed that at the xcodebuild the keychain is specifed that should be used for signing
reverted that the infoplistModify dependency is always added.
Merge branch 'sign-with-xcodesettings'

Conflicts:
	plugin/build.gradle
	plugin/src/main/groovy/org/openbakery/KeychainCreateTask.groovy
prepared for release 0.8.0