Fix Indentation linter with multi-line selectors

The `Indentation` linter had a bug where the following would erroneously
produce an error:

    .class1,
    .class2 { margin: 0; }

This was due to the linter not taking into account selectors that
spanned multiple lines.

Change-Id: I9bed8cc615eb16fb8d74ecfd4b9f57b0aad8d08a
Reviewed-on: http://gerrit.causes.com/38454
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>
Additional test cases for indentation linter

Change-Id: I225748c7cab20c8d5211c308e5ca8808a436a943
Reviewed-on: http://gerrit.causes.com/38455
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>