Small fixes for release candidate 2

Closes #12 (closed)

• Exception message when last component size of output tensor shape is -1
• Handling tensors names in alphabetical order (signaturedef.inputs() and signaturedef.outputs() order is completely random!) now throws a warning when there are > 1 available tensor name in the graph. Add a blacklist to avoir confusion between users placeholders and input tensors.
• Fix: input users placeholders actual names are now resolved

Also closes #1 (closed), #3 (closed), #6 (closed), #7 (closed), #8 (closed), #10 (closed), #11 (closed)