Skip requiring active_resource in Rails 4
Use `get` instead of `match`

Because Rails4 doesn't support `match`.
Parameter shouldn't be convert to numeric

THIS IS A BREAKING CHANGE.

The values of `params` should be given as a `String`.
And Action Pack 4 expects these to be instance of `String`.
Now working on Rails 4
Avoid warning about `secret_token` in Rails 4

When `config.secret_token` is used, rails 4 puts the following warning.

```
DEPRECATION WARNING: You didn't set config.secret_key_base in
config/initializers/secret_token.rb file. This should be used instead of
the old deprecated config.secret_token in order to use the new
EncryptedCookieStore. To convert safely to the encrypted store (without
losing existing cookies and sessions)
```
Avoid warning about `whiny_nils` in Rails 4

Rails 4 says:

```
DEPRECATION WARNING: config.whiny_nils option is deprecated and no
longer works.
```
Use serure source on Gemfile
Update Gemfile.lock
Add gemfiles/*.gemfile into version control
Don't test Rails 4.0 if RUBY_VERSION < 1.9.3
Add travis icon to the README

[ci skip]
Update versions of Rubies and Rails
Fix Appraisal file (the version of rack-test)
Fix .travis.yml (script)
[ci skip] Update Rakefile
[ci skip] Bump version to 0.4.0.pre