Fixed comments parsing

First bug
------------
Comments in which the first character was `*` parsed incorrectly. The other part of the comment was joined with next token. You can reproduce this issue using this comment: 
```
/** Perfectly valid **/
```
I found and solved this bug very quickly. Set second argument of consumeUntil() call in consumeComment() method to `true` and all will work perfectly. But second bug made me rethink consumeComment() routine.

Second bug
------------
Almost all places where consumeUntil() method was used had bug with comments parsing. Here they are:
*  Getting media query for @import rule. If comment was between query and terminated semicolon then this comment was included in query.
* Getting arguments for unknown AT rules. If comment was between arguments or before `{` then this comment was included in arguments.
* On selectors parsing if comment was between selectors or before `{` bracket then selectors will contain this comment.
I have decided to make comments remove right in consumeUntil() method because it is the root of the bug and every place which use it, is buggy.

I have added test for comments. You can compare result before and after this commit.