Mention that Jekyll must not run in safe setting
Fix Jekyll command for building fixture site
Add Rake task for watching site fixture
Fix ministamp and minibundle usage for layouts

This fixes the bug causing thrown exception when ministamp tag or
minibundle block is called multiple times with same asset source as
argument. Because this is very common with layouts, it must be allowed.

Also, this removes the restriction of disallowing the use of static
files as asset sources: you can now use Jekyll's static files as asset
sources for Minibundle. Even though doing this is silly (resulting in
duplicated assets in the output directory), the restriction was
artificial now that a proper mechanism was found for the bug mentioned
above.
Separate log source from message with colon
Add tests for allowing static files to be used as sources to asset files
Explicitly disable safe setting for test fixture
Ignore .bundle/
Tested with MRI 2.1, too