Add args to disable rrdp/http, update docs and setup script.

Add args to disable rrdp/http, update docs and setup script.

+The new arguments are 'rrdp-disabled' and 'http.disabled', both are treated as flags.
+Update docs to include: new arguments, rrdp support, new 'libxml2' dependency.
+Update configuration file example to include new arguments.
+Fix bug at arguments whose value is expected to be a path, this '--tal=' was treated as valid when it isn't, so validate that no empty paths are received.
+Update unit tests impersonator with new args.
+Updates at setup script:
- Fix bug: paths that included a space in between, weren't correctly utilized.
- Use wget always.
- Ignore case when accepting ARIN's RPA.