revert specs2 dependency

https://twitter.com/specs2org/status/456945236128698368
version := "1.1.0-SNAPSHOT"
Update README.md
Remove implicit DateMidnightOrdering since it had been marked as deprecated and it would be removed already
Change version
Merge pull request #59 from kmizu/r/remove-implicit-datemidnightorderning

Remove implicit DateMidnightOrdering since it was planned in 0.6.0
toInterval for RichString
Merge pull request #60 from wookietreiber/wip-rich-string-to-interval

toInterval for RichString