Windows correctForSomethingPath fixes

The _correctForPluginsPath_, _correctForResourcesPath_ and _correctForFrameworksPath_ functions try to fix paths by removing a specific part followed by a slash.

The problem is that these fail when run on a Windows machine, as that uses a backslash as path seperator.

You can see this incorrect behaviour for example in the _.pbxproj_ file when adding plugins to a Cordova project on a Windows machine.

These suggested changes make the replace work for both slash and backslash path seperators.