Implemented elementwise max layer
lint & reduce gradient check stepsize to pass checks
Merge pull request #1053 from jeffdonahue/to3i-elem_max_layer

rebase and fixup #688 from @to3i: elementwise max
Fix lmbdb travis with openldap
Merge pull request #1067 from bhack/lmdb

Get lmdb from openldap
Produce the layers using the abstract factory pattern for simplicity
No more duplication in the layer factories