Added CSIGN, SWAPalpha and Berkeley gates and simplified base case of other gates
Changed control1&2 to list of controls in fredkin and toffoli
Merged control variables into a single list for gate expand 3 to n
Modified unit test for test_gate to use controls list
changed default value of controls list
fixed bug in gates.py
bug fix in gates.py
Merge pull request #136 from anubhavvardhan/add_gates

Added CSIGN, SWAPalpha and Berkeley gates and simplified base case of other gates