Add ability to query the log file and app delegate properties

There are two commits, one for query-log and one for app-props.

The query-log commit adds the ability for the cucumber code to issue a query to retrieve selected records from the iOS log file. The app can add specific tags to log messages that can then be used as keys to retrieve those messages from cucumber.

The app-props commit adds the ability for the cucumber code to call property getters and setters on the UIApplicationDelegate object. It uses keypath notation to allow drilling down into other objects that are referenced by the app delegate. For example, the app could add a property "activeNetworkRequests" that keeps track of open connections, and the cucumber code could wait until that value is zero before doing its assertions.

I have not used cucumber/calabash much, so there may be better ways of doing this.

These files are modified copies of other files in the distribution, so they are derived code and thus fall under the original copyright of those file.