Fix/support dash in relative links

Currently if you go had something like this: `[Some Link](../)`
and you were in `http://devsite.dev/dev/docs/my_module/en/server-setup/location-specific/`

The parser will resolve the link as: `http://devsite.dev/dev/docs/my_module/en/server-setup/location-`

This is because the regex is only matching *Any word character (letter, number, underscore)*. I've added the dash.
Merge pull request #34 from trev/patch-1

Fix/support dash in relative links