[NX-549] Refactor main supportzip api bits into java classes for simplicity.
[NX-549] Extract supportzip api
[NX-549] Add logger config for supportzip package.  Remove direct dep on nexus-atlas-plugin, no longer needed to contribute to supportzip anymore.
NEXUS-6692:  Fix url validation and error handling

Changes:
* the regex was too strict, not allowing port numbers nor localhost with paths
* on repo creation, the validation error was swallowed (wrapped into another config ex)
* on repo update the validation was not handled resulting in generic config error
* aligned regex in legacy and rapture UI
Merge pull request #635 from sonatype/NEXUS-6692-fix-url

REVIEW NEXUS-6692:  Fix url validation and error handling
Merge pull request #633 from sonatype/NX-549-extract-supportzip-api

REVIEW: [NX-549] extract supportzip api
NX-485: replace legacy plugin-repository with Karaf system repository
Fix nexus-testsuite-support ITs (located separate to testsuites)