Remove devtools for Ruby 1.8.7 compatibility
Remove unnecessary magic encoding comment
require 'memoizable/version'

Because require hashes based on the string, not the expanded path of the file,
it's important that we require the version file the same way that it will be
required elsewhere to avoid constant warnings.
Add myself as an author
Update gemspec
Fix issue on Ruby 1.8.7 where methods return negative arity
Replace ThreadSafe::Hash with ThreadSafe::Cache