configurable API host

Override host for mixpanel requests (for dev/testing/etc) with init option:

mixpanel.init(token, {host: 'example.com:1337'});

people.union support

people.union() merges a given list or value with a list-valued people analytics property, excluding duplicate values.

add batch import

import_batch() sends a list of events to Mixpanel using the import endpoint.

fix callback behavior in track_charges when no properties supplied

v0.1.1

fix callback behavior in track_charges when no properties supplied

updated dependencies and metadata

• dropped support for node <0.10
• added iojs and node 0.12 to test matrix