Define wrapped on BasicObject

Necessary for delegators and proxies. Without this change, you get a wrapped
instead of the delegator/proxy target instead.
Add binstubs for rspec, rake

This allows us to avoid doing `bundle exec` for everything.
Restrict gempsec to compatible RSpec versions

After RSpec 3, `should` is not defined by default.
Rename #try to #flat_map

* #try already means something else in Ruby
* #flat_map is a Rubyish name we can borrow from Scala