Possubly fixed Issue #11
Merge branch 'master' of https://github.com/Purdue-ACM-SIGAPP/SafeWalk

* 'master' of https://github.com/Purdue-ACM-SIGAPP/SafeWalk:
  Fix another typo
  Fix typo
  Bump Android API target to API 19
  Fix travis config
  Add Travis CI configuration file
  Fix debug signing key in Gradle build.
  Fix incorrect version of android-async-http in gradle build file.