fix CHANGELOG

#1025 removed the `:value` option, not the `:input_html => { :value => '...'}` option
remove rails < 3.1 stylesheet doc from readme

rails < 3.2 is deprecated, old assed installation is no longer needed
Merge pull request #1067 from timoschilling/patch-2

remove rails < 3.1 stylesheet doc from readme
Merge pull request #1066 from timoschilling/patch-1

fix CHANGELOG for value option
add ROADMAP file to track deprecations
rename to DEPRECATIONS
Merge pull request #1068 from justinfrench/roadmap

Add DEPRECATIONS file