* Elminates a lot of logic in the AnsibleComposer class.
* Update tests with new column offsets. The rule should now be
consistently: Column is the start of the entry's value (so for
strings, the first non-space after the entry beginning, for dicts, the
first character of the first key)
* Changes AnsibleConstructor so that only unicode strings are returned
(no str type)
* Tracks line, column numbers for strings
* Adds unittests for AnsibleLoader (generic for all the yaml parsing)
