Rails3.use?: use String#include? instead of =~

closes #53
update to bundler 1.3.0.pre.5
update changelog
print warning when removing windows generated Gemfile.lock
bump to v47
display the ruby version change to the user
update changelog
Merge pull request #62 from cjolly/cjolly-log-windows-gemfile-lock-removal

print warning when removing Gemfile.lock generated on windows
Merge pull request #54 from heroku/rails3-detect-file-encoding

Rails3.use?: use String#include? instead of =~
Install libgd-dev headers into slug
Run rake extensions:build during compilation
ICU4C 49.1.2
PostgreSQL 9.2.2 client binaries: psql, pg_dump