Refactor headless build support

Use DS. Makes it much easier to add support for other headless
build setups.

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
Refactor version control ignores support

Use DS. Makes it much easier to add support for other version
control ignores setups.

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
HeadlessBuildPlugin: add VersionControlIgnoresManager to the setup method

The Gradle plugin needs access to it.

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
Add Gradle headless build plugin

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
Deprecate the Ant headless build plugin

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
Add gradle build template

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
Install the Gradle wrapper in the workspace

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
cnf: gradle: add class cycle checks

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
build: gradle: add p2 generation

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>