Validate FieldPermission input on save

model_name and field_name must be valid Authorizables
Fix route function to support positional args
make update_plot_and_tree work for species
Breakup FieldPermission validation to catch more

As was commented on e7967a3, we shouldn't swallow up the original
exception, it makes debugging harder. Now we catch and provide better error messsages.
Merge pull request #258 from steventlamb/topic/field_perm_mgmt_endpoint

Topic/field perm mgmt endpoint
Add views for routing and updating plot detail
Change translation function alias to trans for consistency with other files
Use unicode instead of str for display value in field templatetag
Add helper method to UDFModel for use with the field templatetag
Convert plot detail to use field templatetag for display
Remove display style instead of using inline-block for editing
Mirror changes to select fields in inlineEditForm.js
Wire in edit/save/cancel functionality to plot detail to show/hide inputs

Conflicts:
	opentreemap/treemap/templates/treemap/plot_detail.html
Display empty string if value is None
Save current typeahead datum, add function for retrieving it
Add typeahead support to inlineEditForm
Modify species_field.html for use with inlineEditForm.js
Move mustache templates above script block so they are available in "init"
Add typeahead support to plot detail form
Merge pull request #250 from maurizi/topic/editPlotDetail

Edit plot detail