Fix Maven build

Flexmojos seems to be confused by the overlap between sources and
resources.
This fixes the build by moving metadata.xml into a separate resources
folder.

This also breaks the Ant build the will hopefully be fixed in a later
commit.
Move maven-runonce scripts (1)
Move maven-runonce scripts (2)

Those scripts were not working too well when run in the directory with
the project pom.xml
Additionally, the "-s settings.xml" option was not necessary
Edited Maven-README.md to reflect these changes
Prospective ant build fix

I cannot run Ant to check, but this should fix the build after moving
metadata.xml.