entity_metadata_field_text_get throws notices if field is empty

When entity goes to validate / sanitize a body / longtext field it calls this function for output. The problem arrises when there is no text set in the text field / the field isn't set at all on the entity. This causes the field to throw property / array value not set notices all over the place. This becomes especially apparent when utilizing a project like restws which can make calls like /node.json to return all nodes in a site in json format. This call causes empty fields to be transmitted as output (and their output sanitized) where as a normal loading of the node via http call won't try and sanitize empty data.

Patch in bound, very simple to test for and resolve.