Silent exit code 2 for unavailable tools

[jquast]

When landscape.yml or prospector.yaml declares to run a tool that is not installed, nothing happens and exit code 2 is returned by prospector.

Only when the --direct-tool-stdout argument is used, the true reason may be revealed, transcript follows:

$ cat .landscape.yml
frosted:
    run: true
$ cat xyz.py
bad syntax
$ prospector xyz.py
$ echo $?
2
$ prospector --direct-tool-stdout

Cannot run tool frosted as support was not installed.
Please install by running 'pip install prospector[with_frosted]'

$ prospector --version
prospector 0.11.7
$ python -V
Python 3.5.1

Suggest such output is revealed without use of --direct-tool-stdout

[carlio]

Oops that used to happen but I must have accidentally squashed it when trying to hide extraneous pylint output. I'll restore it, thanks!

[carlio]

Ok fixed in develop branch, will make it into next release shortly

[carlio]

@jquast actually I discovered another issue here, turns out that pyroma 1.8.3 has a strange import loggings line which causes it to break and prospector was pinned to <2.0. You may run into further pyroma errors unless you manually upgrade pyroma. I'll fix the setup.py to not be so restrictive too.