argparse: drop optparse for argparse

Cleanups to come later.
argparse: use help string variables instead of constants
argparse: drop redundant parameters
argparse: reflow add_argument calls
travis: test for PEP8 conformance

Include a travis specific requirements file.
PEP8: E111 indentation is not a multiple of four
PEP8: W391 blank line at end of file
PEP8: E261 at least two spaces before inline comment
PEP8: E502 the backslash is redundant between brackets
PEP8: E231 missing whitespace after ','
PEP8: E251 unexpected spaces around keyword / parameter equals
PEP8: E302 expected 2 blank lines, found 1
Docs: Fix typo
Docs: Remove trailing blank spaces
docs: revise installation docs

Based on my installation on my local computer add a bit more info to
assist first time installers.
license: Add GPLv3 license file
license: update headers
Docs: some cleanups
License cleanups
More license cleanups