PDI-9848 - Mappings destroy metadata (when the Mapping input specification does not include all fields)

There are fix and unit tests.
PDI-10420, PDI-10419 - add help button, modify help dialog

 + Added help button to XUL based step/job entry dialogs
 + Add Help to context menu for steps/job entries in View tab in Spoon
 * Show error message dialog if the documentation for step is not found
 * Show web help after user click Help button/ctxt menu item
[PDI-7741] - Modifying export to slave server to use post instead of put (put causes problems within tomcat as we only implement doGet and doPost)
Merge pull request #280 from TatsianaKasiankova/PDI-9848

PDI-9848 - Mappings destroy metadata (when the Mapping input specificati...
Merge pull request #319 from brosander/PDI-7741

[PDI-7741] - Modifying export to slave server to use post instead of put...
Merge pull request #302 from askdzmitry/PDI-10420

PDI-10420, PDI-10419 - add help button, modify help dialog