Change the name of SkFlags to SkCommandLineFlags.
This name is more specific to what it actually does.
Also move the code into tools/flags, to (slightly) better organize
the massive tools folder.
Update the programs that use it to use the new names.
No functionality changes.
BUG=https://code.google.com/p/skia/issues/detail?id=1173
Review URL: https://codereview.chromium.org/12440067
git-svn-id: http://skia.googlecode.com/svn/trunk@8304 2bbb7eff-a529-9590-31e7-b0007b416f81
