Merge pull request #1 from mgaller/master

fixed demo
improved docs; added help-text container
added docstrings
add form-row in non-display-field/fieldsets state too
removed empty line
prevent error when option are empty
take attribute extra_classes on field_descriptors into account
added basis schnipp.dynforms theme
added styling for dropdownselect
added a set method to observable_list
observable_list.remove: no longer trigger removed event on the element itself

-> code relying on such functionality needs to be adapted to delegate the removed event of the list to the removed element
observable_list refactor:

- extracted superclass object_list that provides a list with event support for plain objects
- observable_list is now subclass of object_list and uses observables internally (like before)
- constructor parameter modifier has been removed
- schnipp.models.selectable_list_refinement adds support to track a selected element of the list
refactored ui.SingleSelectListView

- extracted _handle_click method
- renamed select_element to _update_view_selection
added PhantomJS as default test browser and added option for single run
changed dialog min width
decreased fieldholder padding
dropdown is now display-inline
supress command output in Makefile help target
mark required field labels; fixed validation issues
made input tag self-closing