Merge pull request #15 from iarna/js-regex-charclasses

Improve javascript regex character class handling
Fix Python decorators highlighting

As per PR https://github.com/cmur2/joe-syntax/pull/16 from @avli it does:

This fixes highlighting of the decorators with arguments. For example, the following code highlighting was broken:

```python

@first
@second("arg1", "arg2")
def my_fun():
    pass

```
Fix markdown metadata
Apply my colors
Add support for shebangs at the start of javascript files