Add `use Noodlehaus\Config;` in README.md

* release/0.9.0:
  Updated `CHANGELOG.md`
  Close hassankhan#55. Unset cache after a set (another case)
  Close hassankhan#55. Unset cache after a set
  Fixed code sniffer errors
  Added unit tests for Iterator methods and implementation as a whole
  Fixed explanation in docblocks for current and key
  AbstractConfig implements Iterator; added declaration and five needed methods
  PSR-2
  Closed hassankhan#44.
  Add documentation for all method
  Add all() method to AbstractConfig.php, ConfigInterface.php and add test. Close hassankhan#48.
  Fix hassankhan#49.
  Remove !$temp check to fix loading an empty array
  [ci skip] Names update
  Some refactoring in `Config`
  General fixes, updated tests
  Update .gitignore
  Remove remove ùethod
  Add has and remove methods

* release/0.9.1:
  Updated Travis CI configuration

* release/0.10.0:
  Updated `CHANGELOG.md`
  [hassankhan#66] Check if the configuration key exists instead of assuming that a null value equals the configuration doesn't have the requested key.
  Add support for .dist extensions files
  rearrange error handling to reach 100% test coverage;
  PSR2 corrections as generated by PHPCBF;
  provide package-level exceptions, so that callers can catch at the package level;

* release/0.11.0:
  fix for issue hassankhan#86 (hassankhan#87)
  removed unused variable
  expand dotted keys from ini-files
  use static method to obtain supported extensions
  Add remove function in AbstractConfig. Close hassankhan#76

* release/0.11.1:
  Fix markdown for contact email address

* release/0.11.2:
  [ci skip] Add note to `README.md` about PHP support
  Add PHP 5.6, 7.0 to `allow_failures`
  Attempt to fix Travis build errors