[FIXED JENKINS-22334] Use "emulator-" instead of "localhost-"

- This fixes a bug with recent versions of the Android SDK-tools which would cause the test runner to crash before running any tests
- Proven to work on a local Jenkins instance with both Ant & Gradle plugins
  + Jenkins ver. 1.560 / Jenkins Gradle plugin 1.23 / Ant Plugin 1.2
  + Android SDK Tools 22.6.2 / Android SDK Build-tools 19.0.3
- Updated AndroidEmulatorContext.java