Remove offensive language from Readme.md

Replaces "insanely" with "incredibly" to avoid associating mental illnesses with being unreasonable or extreme. Lydia Brown explains it better than I could at http://www.autistichoya.com/p/ableist-words-and-terms-to-avoid.html
Merge pull request #428 from ashaindlin/patch-1

Remove offensive language from Readme.md