Add addRoute method to Slim/Router

Description
========
Simple method that accepts a Route object and adds to the collection in the Router.

Justification
=========
Many custom routing configurations methods using the Slim framework favor creating their own Slim\Route objects.  This change allows adding these routes without relying on the Router mapping methods.

Tests
====
PHP Unit reports the same 3 failures as with the master branch:

    PHPUnit 3.7.1 by Sebastian Bergmann.
    
    Configuration read from /home/naicweb/apps/slimfork/phpunit.xml.dist
    
    ...............................................................  63 / 352 ( 17%)
    ............................................................... 126 / 352 ( 35%)
    ................F..F........................................... 189 / 352 ( 53%)
    ..........
    
    foo
    ....F................................................ 252 / 352 ( 71%)
    ............................................................... 315 / 352 ( 89%)
    .....................................
    
    Time: 2 seconds, Memory: 5.50Mb
    
    There were 3 failures:
    1) SlimHttpUtilTest::testEncryptAndDecryptWithValidData
    Failed asserting that false is true.
    
    /home/naicweb/apps/slimfork/tests/Http/UtilTest.php:86
    /tools/webapps/php/5.4.12/bin/phpunit:46
    
    2) SlimHttpUtilTest::testEncryptAndDecryptWhenKeyAndIvAreTooLong
    Failed asserting that false is true.
    
    /home/naicweb/apps/slimfork/tests/Http/UtilTest.php:124
    /tools/webapps/php/5.4.12/bin/phpunit:46
    
    3) SessionCookieTest::testSessionIsPopulatedFromCookie
    Failed asserting that two arrays are equal.
    --- Expected
    +++ Actual
    @@ @@
     Array (
    -    'foo' => 'bar'
     )
    
    /home/naicweb/apps/slimfork/tests/Middleware/SessionCookieTest.php:93
    /tools/webapps/php/5.4.12/bin/phpunit:46
    
    FAILURES!
    Tests: 352, Assertions: 646, Failures: 3.