Add --quiet flag

[ahazem]

Hi,

Implements #1764.

I noticed that running rake test returns a failure:

[ 93/311] TestGeneratedSite#test: generated sites should ensure post count is as expected.  = 0.23 s
  1) Failure:
test: generated sites should ensure post count is as expected. (TestGeneratedSite) [/users/*****/desktop/dev/oss/jekyll/test/test_generated_site.rb:17]:
<37> expected but was
<38>.

Apparently the test is failing because a2fd8ba added a file (named 2013-12-20-properties.text) in source/_posts directory without adjusting the number to 38. However, I thought I would leave this up to you guys to change.

[parkr]

👍 from meh. @mattr-?

[parkr]

@ahazem The error you mention there should be fixed upstream. Mind rebasing for me?

[ahazem]

@parkr done. :)

[parkr]

Did you force push? Still seeing the same error in Travis.

[ahazem]

Hmm, I did. I'm not an expert but could it possibly be that you need to restart that build? The details on travis shows that the build finished yesterday.