Enable Xcode 6 simulator keyboards by default

## Description
- This is related to https://github.com/calabash/calabash-ios/issues/511
```
Xcode 6 simulator has a new option "Connect Hardware Keyboard". It seems to be on by default. The native keyboard will not appear in the simulator if this option is active.
wait_for_keyboard will wait forever if the native keyboard does no appear.
```

## What this fix entails
Simply by adding the below to `com.apple.Preferences.plist` under `CoreSimulator/Devices/{udid}/data/Library/Preferences/` makes the native keyboard appear without toggling the `Connect Hardware Keyboard` button manually.

```
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>AutomaticMinimizationEnabled</key>
	<integer>0</integer>
</dict>
</plist>
```