WIP reset app and sim content and settings

**FORCE PUSHED** Jun 19 13:40 CET

## motivation

Users are reporting RESET_BETWEEN_SCENARIOS is not working.  I determined that it is working, but that there are some subtle problems in the `reset_app_jail`.  

This work also prepares for iOS 8/Xcode 6.

* marks `reset_app_jail` as deprecated, but does not emit the standard deprecation log message
* `reset_app_sandbox` replaces `reset_app_jail`
* `reset_app_sandbox` no longer emits warning about a missing app 
   - `directories_for_sdk_prefix` can return 7.0 and 7.0-64 - if the app is not found in one of these directories, a warning is emitted
   - now takes an `opts` hash instead of 2 optional arguments.

## todo

- [x] @krukow needs to review proposed deprecated reset_app_jail (replaced with reset_app_sandbox)
- [ ] remove deprecated warning from reset_app_jail - we want to deprecate silently.
- [ ] resolve iOS 6 and 64b flickering cucumber tests
- [ ] resetting the keychain does not work on XTC (separate issue, but one that I need to track here for now)

## testing

Using https://github.com/calabash/calabash-ios-example/pull/5

```
# get the test project
git clone git://github.com/jmoody/calabash-ios-example.git
git checkout -b jmoody-demo/reset-btw-scenarios master
git pull git@github.com:jmoody/calabash-ios-example.git demo/reset-btw-scenarios

1. $ cd calabash-ios-example
2. $ ./run-tests.sh
3. optionally enable more simulators in run-tests.sh
4. optionally change the ruby version
```

- [x] cucumber for ruby 1.9.3, 2.1* for all simulators
- [x] cucumber for ruby 1.9.3, 2.1* for devices [1]
- [x] rspec for ruby 2.1.2
- [x] xtc https://testcloud.xamarin.com/s/Wv4zo51LXTD_gA

[1] smoke tests; these changes are simulator only

## links

* http://stackoverflow.com/questions/24493634/reset-ios-app-in-calabash-ios/24521084
* https://github.com/calabash/calabash-ios/issues/376