Add Obsolete decorator
Use Ruby 1.8 syntax for lambda
Use constant for default formatter
Suppress a warning

This commit removes below interpreter warning.

* instance variable @{ivar} not initialized
Change name: Obsolete -> Deprecated
Merge pull request #10 from KitaitiMakoto/obsolete

Add Obsolete decorator
Merge pull request #11 from kachick/improve-remove_warnings

Suppress a warning  "instance variable @{ivar} not initialized"
Make the example in the README runnable.
Update travis rubies list
Added RSpec example to highlight that the memoize decorator is not able to
handle multiple memoized methods on the some object.
Update README.md
Prevent different memoized methods in the same class from sharing a memos
Merge branch 'memoize_fix'
Fix rspec deprecation warnings
0.9.4