Work towards enabling automatic RAT checks

This commit enables the Apache RAT (Release Audit Tool) plugin to be run
as part of each build which will help spot any potential licensing
issues as early as possible.

Currently this will cause the builds to fail hence why this is in a
branch while I work to figure out all the appropriate excludes and/or
addition of missing license headers
Work on getting rat:check to pass

Added license headers to various files in jena-core that needed them.
Added excludes for test resources because historically Jena has large
numbers of small test files and it is unclear if we can just blanket add
the license headers to them.  They are all covered by the original SGA
to the ASF or by subsequent ICLAs so from an IP perspective are clean
anyway
RAT checks passing for Jena Core

Adds appropriate excludes and missing license headers
Get remaining modules to pass RAT checks

This commit gets the remainder of the code base to pass the RAT checks.
Relevant exclusions are added or files have appropriate license header
added.  Where exclusions are present they are justified in the
jena-parent POM for future reference.
Add license
Add license headers
Add license headers
Remove old stuff
Remove exclusions that no longer need excluding
Clarift position of 'testing' files
Merge branch 'rat-checks'

This merges in the improvements to the build process that include running
the Apache Release Audit Tool (RAT) checks during the build process
which helps to ensure that any potential IP issues such as missing/incorrect
license headers are caught ASAP