.gitignore tweaks

[drmuey]

1. We probably shouldn't ignore .perltidyrc because if once exists I want to know about it so that I can remove it and fallback to my main one. Otherwise I might be silently mis-tidying the code.
2. Seems odd to ignore the travis CI file, if the project uses travis CI we'd have the file in git, if it does not we don't need to ignore it. If a 3rdparty is using travis CI with it then either they’d keep it in RCS in theri fork/branch. Otherwise I’d also want to know I had an arbitrary CI file in my directory. Also, if we do it for travix CI what about gitlab, go.cd, bamboo, Jenkins, etc config files? seems like a slippery slope ;)