Replaced remainaing owner terms with maintainer (text changes only)

Looks like I forgot some text changes in https://github.com/chocolatey/chocolatey.org/pull/49, e.g.:
![1](https://f.cloud.github.com/assets/4357973/1827187/6422d4d8-7229-11e3-9fda-863b33107d19.png)
![2](https://f.cloud.github.com/assets/4357973/1827188/6959d76c-7229-11e3-8767-24818f0fd408.png)


This pull request replaces them with our desired *maintainer* term.
Let’s get rid of this stupid and inappropriate owner term. :smiley: