Various url fixes
- fix url conflicts (#261 (closed))
- improve urls consistency (eg: make all Webapp url start with /apps/, rename /jobs/abort/ID as /jobs/ID/abort, ...)
- support legacy urls (#249 (closed))
- remove superfluous ending slashes in urls (by convention urls ending with a '/' are meant for listing a directory. Thus it is menaningful to put a slash on all urls that list resources (i.e. XxxxxList views) but not on simple actions on a resource (eg: update, delete, ...))