fix all "Relative import" problems from pylint, standardize access to util

This standardizes the way to access the stuff in otrapps.util and makes
pylint happy, so we have nice clean Python code.

refs #1888
keysync-gui: move setup code into App.__init__() to limit global vars

This keeps the "main()" very tiny, with ROOT as the only global var.
keysync-gui: inside the App class, use self instead of root

root is an instance of App, so it the class should not be referencing an
instance of itself.
keysync-gui: rename global var 'root' to 'ROOT' following python conventions
fix pylint complaints about style

* Missing docstring
* Invalid name "fileMenu" (should match [a-z_][a-z0-9_]{2,30}$)
* Unused import
* Unnecessary semicolon
* Comma not followed by a space
* Redefining built-in 'dir'

refs #1888
standardize shebang on: /usr/bin/env python

Packaging will rewrite it as needed, like Debian will rewrite it to
/usr/bin/python.  This one is the most flexible, it works basically
anywhere, including virtualenv.
jenkins.sh: add pylint error checking

Eventually we should enable more pylint stuff, like warnings and more.
Right now there are just too many to deal with...

refs #1888
jenkins.sh: make pylint handle the hashlib hash classes properly

hashlib uses some magic to load whatever is built into the local openssl.
pylint gets confused by this, so we need a pylint plugin to trick pylint
into thinking everything is good.

refs #1888
otr_private_key.py: remove non-existent function and variable
jenkins.sh: write pylint output to a file for Jenkins Violations to parse

refs #1888
jenkins.sh: run pylink on keysync and keysync-gui last since they break more
jenkins.sh: only exit with error on ERROR or FATAL from pylint

refs #1888