Fixed timestamp format: removed 'Z' at the end

TeamCity not fully support ISO 8601 so we need to cut off 'Z' suffix.

See:
  * http://youtrack.jetbrains.com/issue/TW-36173
  * http://en.wikipedia.org/wiki/ISO_8601#UTC
Merge pull request #10 from anton-rudeshko/iso-timestamp

Fixed timestamp format: removed 'Z' at the end