Brackets competion should transparently handle closing tags

[Zisu Andrei]

Wasn't sure what to write in the bug title, but the problem is the following:

When brackets completion triggers (i.e. when I type a "{" character), it will automatically add
a "}" character, which is helpful.

However, since this is meant to be just an aid to the developer, if he types in "}" afterwards, it shouldn't add a second bracket, resulting in "}}". Instead, it should just skip the bracket that was previously inserted.