ENH: use paginator for next and previous objects
ENH: use paginator for next and previous objects

next_submission(), previous_submission()
next_revision(), previous_revision()

Improve code using django.core.paginator

ksurya/SciPyCentral,Srisai85/SciPyCentral,scipy/SciPyCentral,scipy/SciPyCentral,wqshi/test,scipy/SciPyCentral,Srisai85/SciPyCentral,ksurya/SciPyCentral,wqshi/test,Srisai85/SciPyCentral,ksurya/SciPyCentral,wqshi/test