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

Make mass assignment to attr_protected model medium confidence

Conflicts:
	CHANGES

Use exceptions instead of abort in brakeman.rb

Medium confidence for mass assignment to attr_protected models

Use exceptions instead of abort in brakeman lib

instead of aborting