Allow removing path prefixes

[vadakr]

Fixes #191

File	Description
WAStoragePublisher.java	- added a removePathPrefix property with a getter/setter - added a trailing slash to it if not explicitly specified
UploadService.java	- modified the signature of getItemPath to accept ServiceData for testability - added a new removePrefix method that does the actual work of removing the prefix from the path
UploadToBlobService.java	- injecting ServiceData into the getItemPath call
UploadToFileService.java	- injecting ServiceData into the getItemPath call
UploadServiceData.java	- added a removePathPrefix property with a getter/setter
Messages.properties	- verbose logging messages when the prefix is being removed
config.jelly	- new 'Remove prefix' option in the UI
config.properties	- a title for the new 'Remove prefix' option in the UI
help-removePrefixPath.html	- help for the new 'Remove prefix' option
UploadServiceTest	- unit tests for prefix path removal in 8 scenarios controlled by 3 parameters - remove prefix path (Y/N), virtual path (Y/N) and embedded virtual path (Y/N)

NOTE: I have not run an end-to-end test!

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your master branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue

[timja]

generally looks ok, but i'll test manually before merge, can you revert all the * import changes throughout