[Jaxrs-*] Java-based generator + unittest for spec/cxf/resteasy

[jfiala]

PR checklist

• Read the contribution guildelines.
• Ran the shell/batch script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh and ./bin/security/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates)
• Filed the PR against the correct branch: master for non-breaking changes and 2.3.0 branch for breaking (non-backward compatible) changes.

Description of the PR

see #4087, generator + unittest für cxf, also updated samples
pls merge PR #4995 first, this PR was branched from jfiala:generator_jaxrs-spec_4087

Currently covered languages/shellscripts:

• jaxrs-cxf
  • jaxrs-cxf-petstore-server.sh
• jaxrs-cxf-client
  • currently no shellscript
• jaxrs-resteasy
  • jaxrs-resteasy-petstore-server.sh
  • jaxrs-resteasy-joda-petstore-server.sh
• jaxrs-spec
  • jaxrs-spec-petstore-server.sh

[jfiala]

@wing328 I added the commandline invocation as well, this is equivalent to the shellscript (see JaxrsSpec_Generator_Petstore.java and JavaCXFServer_Generator_Petstore.java).

Pls review and let me know if I should do some refactoring before copying the java classes for all current shellscripts or if I should leave it as is for simplicity?

[jfiala]

@wing328 I added resteasy default + joda and cxf-client and did some refactorings.
Pls review and merge if it is OK, then the corresponding shellscripts could be removed in the next step.