Multiple plugins with frontend need different xwork package names

[betacore]

Describe the bug
When multiple plugins are developed and deployed, the last deployed plugin will show up the frontend but the previous one will get 404 on loading the frontend because there are conflicts in default xwork package names (webwork, config).

Expected behavior
Multiple plugins can be installed and all frontends will work independantly.

Solution
atlassian-plugin.xml:
add prefixes for xwork package name like:

<xwork key="app-action">
       <package name="$pluginName.webwork" extends="default" namespace="/plugins/$pluginName">
            ...
       </package>
</xwork>

[weickmanna]

@betacore @sjahreis I think there is also a problem with the Javascript name "frontend.js" that would be the same for the different frontend applications and overwrite each other. So I think we also need unique .js file names.

[sjahreis]

@weickmanna I agree