add Maven Wrapper support

[vorburger]

see https://github.com/takari/maven-wrapper

[vorburger]

@rhuss & Co. how about this?

I could use this to throw https://github.com/vorburger/opendaylight-bot on OpenShift...

PS: This will probably conflict with some of my other pending PRs; get those in first, then I'll rebase it.

[rhuss]

LGTM in general, but I wonder whether we should include Maven wrapper support also in the RHEL images.

I.e. to pick up a local mvn when provided in the source code to compile.

wdyt, @jamesnetherton @dhirajsb ?

[jamesnetherton]

I think we should only support this in the community images.

[vorburger]

@jamesnetherton so how exactly do we want to "condition" this? Similar to the Gradle "feature switch" in #121, so if I added a withMavenWrapper true/false to images.yml and {{? fp.config.base.withMavenWrapper }} in the template - would that work for you?

[jamesnetherton]

@vorburger yes, a simple feature switch would be fine.

[vorburger]

this is kind of redundant with line 148 below, but never mind

[vorburger]

@jamesnetherton @rhuss done; withMavenWrapper, for now adds ./mvnw only for community image.

[rhuss]

thanks, lgtm