Increase expectation on output of gclient for help and unknown command.
Increase expectation on output of gclient for help and unknown command.

Also adds msg to assertions to print current size of data written to stdout.

Review URL: https://chromiumcodereview.appspot.com/16058007

git-svn-id: bd64dd6fa6f3f0ed0c0666d1018379882b742947@202863 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

svn2github/chromium-depot-tools,svn2github/chromium-depot-tools,svn2github/chromium-depot-tools