[WIP] Allow numpy.exp(theano_var) to build a graph.

Fix test in float32 and try to run floatX=float32 with python 2.6 in travis.

Added examples to Unique + some flake8 for tensor/extra_ops.py

Flake8 gof

Add elemwise `conj` to `sparse`.

Flake8 scalar

Opt: Alloc(Alloc(...),...) -> Alloc(...) #1902

OpFromGraph.connection_pattern()

Flake8 sparse