replace deprecated optparse with argparse

replace deprecated optparse with argparse

following guidelines from:
https://docs.python.org/2/library/argparse.html#upgrading-optparse-code
except, still using option = parse.parse_args() instead of args = ...

- using the following script in folder fdroidserver:
	for i in *.py; do
		sed -i -e 's/optparse/argparse/' \
			-e 's/OptionParser/ArgumentParser/' \
			-e 's/OptionError/ArgumentError/' \
			-e 's/add_option/add_argument/' \
			-e 's/(options, args) = parser/options = parser/' \
			-e 's/options, args = parser/options = parser/' \
			-e 's/Usage: %prog/%(prog)s/' $i;
	done
- use ArgumentParser argument to replace (option, args) = parser.parse()
  call
- use parser.error(msg) instead of raise ArgumentException as suggested
  in https://docs.python.org/2/library/argparse.html#exiting-methods
- in fdroid catch ArgumentError instead of OptionError