Add DofMap::dof_owner() search
Add DofMap::dof_owner() search

This can be done without the current API, but I'd rather have a
short-to-invoke O(log N_procs) method available in libMesh, not force
users to write a longer O(N_procs) linear search or an even longer
(because we don't give raw access to the _end_dfs array) binary
search.

jwpeterson/libmesh,hrittich/libmesh,libMesh/libmesh,jwpeterson/libmesh,BalticPinguin/libmesh,capitalaslash/libmesh,90jrong/libmesh,pbauman/libmesh,capitalaslash/libmesh,capitalaslash/libmesh,balborian/libmesh,pbauman/libmesh,giorgiobornia/libmesh,pbauman/libmesh,jwpeterson/libmesh,BalticPinguin/libmesh,hrittich/libmesh,BalticPinguin/libmesh,libMesh/libmesh,svallaghe/libmesh,jwpeterson/libmesh,svallaghe/libmesh,hrittich/libmesh,giorgiobornia/libmesh,capitalaslash/libmesh,90jrong/libmesh,roystgnr/libmesh,BalticPinguin/libmesh,roystgnr/libmesh,dschwen/libmesh,svallaghe/libmesh,jwpeterson/libmesh,hrittich/libmesh,hrittich/libmesh,capitalaslash/libmesh,BalticPinguin/libmesh,pbauman/libmesh,balborian/libmesh,giorgiobornia/libmesh,dschwen/libmesh,hrittich/libmesh,90jrong/libmesh,pbauman/libmesh,svallaghe/libmesh,roystgnr/libmesh,libMesh/libmesh,pbauman/libmesh,dschwen/libmesh,BalticPinguin/libmesh,giorgiobornia/libmesh,giorgiobornia/libmesh,BalticPinguin/libmesh,giorgiobornia/libmesh,pbauman/libmesh,dschwen/libmesh,libMesh/libmesh,dschwen/libmesh,dschwen/libmesh,roystgnr/libmesh,svallaghe/libmesh,libMesh/libmesh,90jrong/libmesh,balborian/libmesh,svallaghe/libmesh,libMesh/libmesh,dschwen/libmesh,roystgnr/libmesh,balborian/libmesh,libMesh/libmesh,90jrong/libmesh,roystgnr/libmesh,giorgiobornia/libmesh,hrittich/libmesh,pbauman/libmesh,jwpeterson/libmesh,balborian/libmesh,dschwen/libmesh,balborian/libmesh,jwpeterson/libmesh,balborian/libmesh,giorgiobornia/libmesh,pbauman/libmesh,svallaghe/libmesh,hrittich/libmesh,90jrong/libmesh,roystgnr/libmesh,svallaghe/libmesh,svallaghe/libmesh,90jrong/libmesh,roystgnr/libmesh,90jrong/libmesh,capitalaslash/libmesh,balborian/libmesh,balborian/libmesh,BalticPinguin/libmesh,capitalaslash/libmesh,hrittich/libmesh,libMesh/libmesh,jwpeterson/libmesh,balborian/libmesh,giorgiobornia/libmesh,90jrong/libmesh,capitalaslash/libmesh