fix($state): change default value of `inherit` option to `true`

Since #970, `href()` method takes into account the `inherit` option. It's a good thing but the default behavior of `href()` is now different because of the `false` default value of `inherit` options. It will result a breaking change in the next release 0.3.0.

Here are 2 plunkers to demonstrate that:
- [Plunker](http://plnkr.co/edit/EX7p2SHgQb5guolM6621?p=preview) with ui-router 0.2.10: params are inherited 
- [Plunker](http://plnkr.co/edit/TzCeSUCKmAUfr4UxTW6Z?p=preview) with ui-router master: params are no longer inherited

To avoid that, I change the default value to `true`. The default behavior is exactly the same as before the #970.

Moreover, I think a `true` default value is more convenient for this "high level oriented" method, like `go()` which has `true` default value too (as opposition to `transitionTo`, a lower level method).

I found the problem when a user of my repository ([angular-breadcrumb](https://github.com/ncuillery/angular-breadcrumb)) has reported an [issue](https://github.com/ncuillery/angular-breadcrumb/pull/13) (thank to you @fwitzke).