Merge pull request #2 from anubhavvardhan/master

Introductory notebook for quantum gates
Merge pull request #4 from anubhavvardhan/master

Complatibility with QuTiP 3.0
link to qubism fixed
Merge pull request #5 from stared/patch-1

link to qubism fixed
Changed unitary_matrix to propagators
Changed unitary_matrix to propagators