Increase max line length to 115 chars

Take max line length to <= 115 characters.

Github's diff view wraps lines of 116 characters or more, so lets use more line space in our code without going crazy. There's at least three of us that have been writing to that standard for a few months, so lets make it official in the guide at last.
Merge pull request #3 from fac/increase-max-line-length

Increase max line length to 115 chars