Andy Rubin, "the father of Android," is back at Palo Alto smartphone startup Essential Products Inc. after taking a leave of absence last month. Re/code cited unnamed sources late on Friday who said Rubin had taken care of personal issues while on leave. The leave was announced, however, just after The Information published a story about an internal Google complaint from 2014 that accused Rubin of having an "inappropriate" relationship with a colleague in the search giant's Android division. Rubin…