Add plugin disovery dialog to toolbar

Adds the plugin discovery dialog to the toolbar of the config editor.
Also adds an icon to the existing LaunchCordovaPluginWizardAction.

Signed-off-by: Gorkem Ercan <gorkem.ercan@gmail.com>
format xml when items added

Formats the newly added elements that were added using the config
editor's UI 

This fixes https://issues.jboss.org/browse/JBIDE-15816
Do not take over config.xml files on other project types

Adds the config.xml content type to nature, also enhances the content
describer to avoid name conflicts.

Signed-off-by: Gorkem Ercan <gorkem.ercan@gmail.com>
layout improvements new sections to overview page

Adds an export and plugin section to the Overview page. Introduces
NativeArtifactExportAction to launch export wizards. Also enhances
LaunchCordovaPluginWizardAction so that wizard can be openend to an
initial tab.

Signed-off-by: Gorkem Ercan <gorkem.ercan@gmail.com>
refactor and improve the layout for properties page

Refactors the code so that all sections are created seperately.Improves
the layouts for buttons. Also changes to use layouts with better margins 

Signed-off-by: Gorkem Ercan <gorkem.ercan@gmail.com>
added icons

icons for export and plug-in wizard are added

Signed-off-by: Gorkem Ercan <gorkem.ercan@gmail.com>
Merge branch 'config_editor_improvements'