Block indent: Change acceptable values

`block-indent` option now accepts only these kind of values:
    - `{Number}` of spaces;
    - `{String}` of whitespaces and tabs. If there is any other character in the
      string, the value will not be set.
Colon space: Change acceptable values

`colon-space` option now accepts only `{Array}` of these kinds of values:
    - `{Number}` of spaces;
    - `{String}` of whitespaces and tabs. If there is any other character in the
      string, the value will not be set.
The first element of array is spaces before colon, and second one is spaces
after colon.
Combinator space: Change acceptable values

`combinator-space` option now accepts only `{Array}` of these kinds of values:
    - `{Number}` of spaces;
    - `{String}` of whitespaces and tabs. If there is any other character in the
      string, the value will not be set.
The first element of array is spaces before combinator, and second one is spaces
after combinator.
Rule indent: Change acceptable values

`rule-indent` option now accepts only these kinds of values:
    - `{Number}` of spaces;
    - `{String}` of whitespaces and tabs. If there is any other character in the
      string, the value will not be set.
Stick brace: Change acceptable values

`stick-brace` option now accepts only these kinds of values:
    - `{Number}` of spaces;
    - `{String}` of whitespaces and tabs. If there is any other character in the
      string, the value will not be set.
Merge pull request #126 from csscomb/tg/116-consistent-values

Change acceptable values (#116)