Android O Support Beta 3

This adds support for Android O by defaulting to using a JobScheduler to run scans on a ScanJob instead of a long-running BeaconService, as long-running services are no longer allowed on Android O.

You can enable ScanJobs instead of the BeaconService on devices without Android O by calling:

beaconManager.setEnableScheduledScanJobs(true);

The above is not needed on Android O, as it is the default setting for that OS version.

Read more details here: #484

To use this release, you must download the aar file below, and configure it with your project like so:

• Edit your innermost build.gradle file to add the beta library AAR as a dependency like so:

      dependencies {
        compile 'android-beacon-library:2.12-beta3@aar'
      }

• Create a /libs folder next to the build.gradle above, then download and copy the the android-beacon-library-2.12-beta3.aar file below into this folder.

• Configure your app's outermost build.gradle File to reference the /libs directory from above in a flatDir declaration:

      allprojects {
          repositories {
              jcenter()
              flatDir {
                  dirs 'libs'
              }
          }
      }