Added compatibility for ruby 1.8.7

* Monkeypatched `Dir` to include `home`
* Changed params for proc
Comparing strings when you want to compare numbers is not the result you will want.

You can do it like this:

```ruby
# option 1
if Gem::Version.new(RUBY_VERSION) < Gem::Version.new("1.9")

# option 2
if RUBY_VERSION =~ /^1\.8/
```

I prefer option 1.