Python 3 syntax errors in lalapps/src/pulsar/Fscan

There are python3 syntax problems in the Fscan python codes.

$ python -m py_compile src/pulsar/Fscan/*.py
Sorry: TabError: inconsistent use of tabs and spaces in indentation (findCombs.py, line 39)
  File "src/pulsar/Fscan/fscanDriver.py", line 182
    extraDatafindTime = 256L
                           ^
SyntaxError: invalid syntax

Sorry: TabError: inconsistent use of tabs and spaces in indentation (plotSpecAvgOutput.py, line 367)

These will need to be corrected for the next release to support python>=3.