crit: add crit

crit is a python script that helps user to manipulate criu
images. For now, it can only convert criu images to\from
human-readable format using pycriu.images module.
crit: add crit target to Makefile and *.pyc to .gitignore
test: add crit test

Test steps:
1) generate img files by dumping loop.sh
2) convert img files to txt files
3) convert txt files to img files
4) cmp original and produces img files

It also uses i/o redirection and --format nice options to
check if they work properly.
crit: add setup.py

This is a small python scipt that uses distutils to install crit script
and pycriu package.
crit: add install-crit target to Makefile

install-crit uses setup.py install --prefix=$(DESTDIR) to act
the way the install target expects it too.