processor host lease prefix not being set.

[aheld]

Describe the bug
Setting storageBlobPrefix in the EventProcessorHost options does not result in a prefix

To Reproduce
Steps to reproduce the behavior:

1. create host with a prefix option

eventType = 'created'
eph = EventProcessorHost.createFromConnectionString(
      EventProcessorHost.createHostName(eventType + '-host'),
      storageCS!,
      ehCS!,
      {
        eventHubPath: path,
        leasecontainerName: 'event-host-processor',
        storageBlobPrefix: eventType + '_'
      }
    )

Expected behavior
A lease is created in the blob store with the requested prefix

Actual behavior
the lease name is just $default, not created-$default

Package-name: azure-event-processor-host
Package-version: ** 0.1.2**
node.js version: 8.10
OS name and version:osx

Additional context
I will attach PR that works for me.

[aheld]

#91

thanks!

[amarzavery]

• azure-event-processor-host@0.1.3