Created filters service for angular app

- Created filters service and integrated into rest/rpc services via route
  provider resolvers.
Add filters to REST and RPC services

- Added filters to each of REST and RPC service scopes
- Create "filters" array on cration of new input
Added scope methods for manipulating filters

- Added addFilter, removeFilter, addFilterOption
- s/addOption/addValidatorOption/ in both JS application and partials
UI for filter creation/manipulation

- Replicated validator UI for filters
- Moved validator/filter UI to a common partial; used ng-include from
  both rpc/rest services to utilize it.
- Currently not working, likely due to not having "filters" returned by
  API.
Ensure we initialize "filters" array

- Just like validators, need to scrub the API return value to see if any
  filters are defined, and, if not, set the result to an empty array.
  Similarly, do this for individual filter options.
Add required field to UI

- Added the required field to the UI
- Added handling when retrieving the input filter to look for a
  "required" field in each input. If not present, casts to "false"; if
  present, casts to boolean.
Merge branch 'feature/46'

UI features related to #56