Make the code PEP8 compliant

[kaivalyar]

Here is the ouput of ../HistManager $ pep8 -q --statistics histmanager-code:

histmanager-code
1       E201 whitespace after '('
1       E202 whitespace before ')'
1       E203 whitespace before ':'
2       E211 whitespace before '('
8       E225 missing whitespace around operator
47      E231 missing whitespace after ':'
86      E261 at least two spaces before inline comment
30      E262 inline comment should start with '# '
7       E265 block comment should start with '# '
2       E266 too many leading '#' for block comment
49      E302 expected 2 blank lines, found 1
181     E501 line too long (81 > 79 characters)
17      E711 comparison to None should be 'if cond is None:'
1       E712 comparison to False should be 'if cond is False:' or 'if not cond:'
12      E721 do not compare types, use 'isinstance()'

All files in this repository need to be made entirely pep8 compliant.