HTML-384: Added support for ajax autocomplete provider to EncounterProviderAndRole tag. To accomplish this I have added support for two attributes. 1. autocompleteProvider which can take values true/false (Dafault is false) 2. providerMatchMode which is used to specifiy how matching is done when the text to be searched is submitted via ajax. This takes one of the three values namely "START", "END", "ANYWHERE" with "START" as default.
Matching is done per standard OpenMRS API (i.e. via ProviderService).
