* `salt.modules.file.contains()`, `salt.modules.file.contains_regex()`, `salt.modules.file.contains_glob()` and `salt.utils.find` now do the searching/matching against chunks of data; using defaults, 32KB chunks of data in files; instead of searching/matching line by line.
* Based on the above changes `salt.states.file.append()`, when checking if the text to append is already present, now uses `salt.modules.file.contains_regex()` in order to match spanning multiple lines ignoring the addition/deletion of white-space or new lines, except inside commas.
* The regex used on the above item is built at runtime using `salt.utils.build_whitepace_splited_regex()`, just feed the text to it and you'll get back the proper regex to the matching/searching on, for example `salt.modules.file.contains_regex()`.
* Added tests for all this code.
