Exclude javafx dependency

[redfish4ktc]

When running SmartBear 5.0.0 plugin with sun jdk6, openjdk6 or openjdk7, execution fails because of the javafx dependency cannot be resolved. See a post in the soapui forum that talks about this.
In soapui 5.0.0, this dep is declared with the system scope, see pom of the 5.0.0 tag and resolution fails because javafx is not installed with the jdk for these distributions.
For me, this is annoying because builds runned by CI jobs in openjdk environments failed because of that.

As mentionned by a SmartBear developer in the post, this dep is used for browsing feature only (including OAuth 2). So as not everybody needs this, I propose to remove this dep and document that it needs to be added when declaring the plugin in a project pom when the feature is needed

Tasks to be peformed

• experiment integration test with
  • SmartBear implementation: locally install a "version does not exist" javafx jar
  • our plugin, remove the dep
• documentation (if solution is working)
  • workaround with SmartBear impl (cf implem or install javafx in a given directory and redeclare the javafx dep with the installation path)
  • our plugin, when javafx dep is needed and how to add it (cf SmartBear workaround)