base: move of remote autocomplete field

* Moves the script for autocompletion from groups module to
  base module.

* Refactoring the script as a RequireJS module that returns
  a FlightJS component.

* Adds documentation on how to use it.

Signed-off-by: Leonardo Rossi <leonardo.r@cern.ch>
Are you sure that is needed the escaping? 
I opened now the docs with firefox and I can see it without problems.

@jirikuncar travis give me back a error only with release.
```python

======================================================================
FAIL: test_no_headers (invenio.modules.editor.testsuite.test_editor.TestPerformDoiSearch)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/build/inveniosoftware/invenio/invenio/modules/editor/testsuite/test_editor.py", line 113, in test_no_headers
    self.assertNotEqual(perform_doi_search(doi), wrong_output)
AssertionError: {} == {}
```
But, I did't touch the editor module! T_T