added sigmoid layer
sigmoid layer cpu and gpu code
fixed copyright
Merge pull request #106 from tdomhan/sigmoidlayer

Sigmoidlayer
add macro for numpy < 1.7

as suggested by @longjon
https://github.com/BVLC/caffe/issues/44#issuecomment-32832810
add shebang to python scripts

for executing in the shell without call to python. Follows the example
of @kloudkl .
python requirements: don't fear the future
define by := (no need for re-expansion)
add SplitLayer and Net::AddSplits to transform shared bottom blobs into
split layers
make split_layer backward obey propagate_down
add split layer tests
add split layer tests
add split layer insertion tests; move split insertion code to util file
some cleanup
eliminate redundant code with get_split_blob_name method
change \n's to less distracting spaces in hard-coded proto strings
give first top split blob same name as bottom blob
allow in place computation of SplitLayer 0th top blob
change \" in test_split_layer to ' for readability
remove pointlessly duplicated CheckGradientExhaustive calls (I screwed
up when merging, I think)