Fix ios privacy mode

PR related to #128

Remove operations throw a `QuotaExceededError` within iOS7 browser running in privacy mode.
```
[Error] Error: QuotaExceededError: DOM Exception 22
setItem@[native code]
A@http://192.168.1.11:9000/bower_components/angular-cache/dist/angular-cache.min.js:10:10493
removeAll@http://192.168.1.11:9000/bower_components/angular-cache/dist/angular-cache.min.js:10:13381
...
```
This fix avoids the execution of `AngularCache.remove` or `AngularCache.removeAll` when disabled is true.

Current 2.x version was also fixed to 2.4.0