Add right value to results in XSS check

Relax slim dependency for Slim 2.0.0

User exit code of "1" when path is not a Rails app

Limit branched value depth, add --branch-limit option

Add more methods to check for command injection

should have been a test that the warning does _not_ appear.

closes #206 finally

Fix output format detection to be more strict again

Allow empty Brakeman config file

and also -f should override detection

fixes #343

because they are already in test/tests/ and
test/tests/test_* just seems silly to me

also fixes a weird issue in Ruby 1.8.7 where duplicate
warnings were getting reported when there weren't any

Fix text report console output on JRuby

Avoid duplicate "Dangerous Send" and "Unsafe Reflection" warnings