Fix pathing bug so `examine_results.rb` can load `./ruby/read_data.rb`

This patch fixes a Ruby pathing error where Ruby is unable to load `./ruby/read_data.rb` when running the following commands:
```bash
% cat test.data | ./ruby/shingle.rb coeff 0.5 > result.1
% cat test.data | ./examine_result.rb result.1
```
The reason for this is because of the line `require 'ruby/read_data'` in the file `./examine_result.rb`. 

The original error, before the change, was:
```bash
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in `require': cannot load such file -- ruby/read_data (LoadError)
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in `require'
	from ./examine_result.rb:25:in `<main>'
```

While, the new output works as expected and prints the following to the console:
```bash
% cat test.data | ./examine_result.rb result.1                                                                                                                                                     
0.72464 (0,2)
	richard's favorite flavour of softdrink is peanut butter and jam
	richard's favorite softdrink flavor is peanut butter and jelly
```
The ruby version I am using, outputted from `ruby --version`, is:
```bash
ruby 2.0.0p247 (2013-06-27 revision 41674) [universal.x86_64-darwin13]
```