CLI version of fontbakery now support only concrete single source file

To run use

python fontbakery.py /path/to/source.[ufo,ttf,sfd,otf,ttx]
Complete CLI bakery process #280 for single files
fontbakery.py now can have several sources and --config argument #280
Documentation of Bakery class, added dummy upstream_tests to implement #280
Interact user when applying fixes #280
Update README.md
help message for fontbakery.py #280
bakery.defaults.yaml has been replaced by cli/defaults.yaml
call ttfautohint with autohint.ttf as output font #337
if devanagary subset selected then put -f deva argument #337
Allow setting vertical metrics individually #333
Fixed result tests unicode error
remove style from family-name, eg. Regular, Italic #334
Added devanagari to supported subsets in genmetadata.py #334
JS that scroll page has been removed at some commit #334
Minor features and changes #334
`git checkout XXXXXX` should be rendered with prefix of command line
Now we use os methods, I'd like the log to show the equivalent shell commands. This means putting for the first line, using a # before the ok instead of in square brackets
Replacing [OK] -> # OK, [FAIL] -> # FAILED
Show the equivalent shell commands in bake log #334