gradle: build v1

*NOTE* This branch will be rebased as fixes are applied.

Currently, the full bndtools build-template.xml ant file (and more) is
implemented. No custom ant tasks yet.

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: minor fix, gradle will figure this out for us

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
bndoc: disable the bnd build phases (the ant build was disabled for bndoc)

Until the dependency on nodejs-less is fixed.

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: add build setup doc/svg

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: relative file URLs are relative to the root project

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: only create the export directory when there are runfiles

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: ignore downloaded build dependencies

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: remove bundle-to-bundle dependency, it's not there

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: show wrapper task separately

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: add dist task in the dist project

Like in the ant build, it generates an OBR index and an R5 index
in the release repository.

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: the default task is now jar, which includes bundle

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: add findbugs to the build (disabled by default)

To enable, mention findbugs explicitly on the command line as a
task to run.

Use the -PCI command line option to generate findbugs xml reports
instead of html reports.

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: improve the custom build setup

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: allow individual enablement of findbugs tasks

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: default task on root project is 'jar'

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: update README.md

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: no need to setup the default tasks of a bnd project

This was already done in the root project

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: upgrade bnd to get really flattened properties

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: update comments in the build files

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

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