Singer-tap-appsflyer

* Fix syntax error in `installations.json` schema from 0.0.6

* Remove the `"format": "uri"` elements from installations json schema

* Syncing in-app-events would take too long so cut the window down and iterate forward [7](https://github.com/singer-io/tap-appsflyer/pull/7)

* Updated the schema for installations to set 'customer_user_id' to allow a string value [5](https://github.com/singer-io/tap-appsflyer/pull/5)

* Updated the schema for in_app_events to set `customer_user_id` to allow a string value [4](https://github.com/singer-io/tap-appsflyer/pull/4)