let's use Apple's `sim` tool to launch iOS simulator binaries.

Both Xcode 4 and 5 have a tool called _sim_ that makes it easy to launch iOS simulator executables with the right environment settings.  If we use _sim_, all the IPHONE_*, DYLD_* variables are done for us, which means we don't have to go out of our way to setup things like IPHONE_SIMULATOR_ROOT or IPHONE_SIMULATOR_VERSIONS.

_sim_ is at --

```
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/usr/bin/sim
```

This PR changes all of the iOS otest-query operations and iOS logic tests to use the _sim_ tool.