[fixed #1441] isActive false positive when URL not finished

[eXon]

This is fixing a huge bug for the isActive. If I had a path starting with /hell and another by /hello, isActive would think /hello is active when I am on the /hell URL. This is perfectly fixed now :)

I wasn't able to write unit tests because karma start was crashing for me. I would get this:
(Looks like Travis was having the same error before my PR)

WARN [preprocess]: Can not load "webpack"!
  TypeError: Object [object Object] has no method 'refreshFiles'
    at Plugin.notifyKarmaAboutChanges (/var/git/thereactivestack/react-router/node_modules/karma-webpack/index.js:108:15)
    at Plugin.<anonymous> (/var/git/thereactivestack/react-router/node_modules/karma-webpack/index.js:72:9)
    at Tapable.applyPlugins (/var/git/thereactivestack/react-router/node_modules/webpack/node_modules/tapable/lib/Tapable.js:26:37)
    at Watching._done (/var/git/thereactivestack/react-router/node_modules/webpack/lib/Compiler.js:78:17)
    at Watching.<anonymous> (/var/git/thereactivestack/react-router/node_modules/webpack/lib/Compiler.js:61:18)
    at Tapable.emitRecords (/var/git/thereactivestack/react-router/node_modules/webpack/lib/Compiler.js:281:37)
    at Watching.<anonymous> (/var/git/thereactivestack/react-router/node_modules/webpack/lib/Compiler.js:58:19)
    at /var/git/thereactivestack/react-router/node_modules/webpack/lib/Compiler.js:274:11
    at Tapable.applyPluginsAsync (/var/git/thereactivestack/react-router/node_modules/webpack/node_modules/tapable/lib/Tapable.js:60:69)
    at Tapable.afterEmit (/var/git/thereactivestack/react-router/node_modules/webpack/lib/Compiler.js:271:8)
INFO [karma]: Karma v0.12.37 server started at http://localhost:9876/
INFO [launcher]: Starting browser Chrome
INFO [Chrome 44.0.2403 (Linux 0.0.0)]: Connected on socket k3-vXGcIA8yu4S8lLBYy with id 79713155
Chrome 44.0.2403 (Linux 0.0.0) ERROR
  Uncaught ReferenceError: require is not defined
  at /var/git/thereactivestack/react-router/tests.webpack.js:1
Chrome 44.0.2403 (Linux 0.0.0): Executed 0 of 0 ERROR (0.047 secs / 0 secs)

[eXon]

This is also fixing #1611 and #1614

isActive('/') should only be true if it is a perfect match (would be useless otherwise)

[eXon]

For the unit tests not running, I have the same problem on my projects. It is due to karma-webpack version 1.7 is the reason of the crash. Using a dependency on ~1.6 and karma ~0.12 seems to do the trick for now until they fix the issues.

[mjackson]

This is fixed in master.