implement tests

this tests only ckeck status code and response body.
implements rake test
rake default task add test
Fix Rakefile, replace system() to sh()
Merge pull request #4 from rnakano/testcase

In Rakefile, change system() to sh()
implements tests

this tests ckeck 4 ENV parameters.

* PATH_INFO
* SCRIPT_NAME
* QUERY_STRING
* REQUEST_METHOD
implements tests for query parameters

This tests check 2 ENV parameters, QUERY_STRING and PATH_INFO.
Tested more complecated url than test_rack_env_simple.rb.
update .gitignore
fix : rake

mv bossan_ext.so to lib/bossan/ from ext/bossan in rake compile,
and set require_relative in test_rack_spec.rb
add test_files in bossan.gemspec
update README
fix: avoid overwrite local variable
Merge pull request #5 from kubo39/testcase

Testcase