Prepare for open-sourcing, no longer need JitPack creds.

useragent override and skipAdvertisingIdDetection (#17)

* Improve unit tests for eidFromURI

* skipAdvertisingIdDetection and useragent override

- OptableSDK constructor now accepts a useragent String argument,
  null by default. When not null, disables WebView based user
  agent detection and overrides with provided value.

- OptableSDK constructor now accepts a skipAdvertisingIdDetection
  Boolean argument, false by default. When true, disables
  AdvertisingIdClient ad info detection which runs in a background
  coroutine. If the caller doesn't use the identify(email: String,
  gaid: Boolean, ppid: String) variant then ad ID detection is
  not needed and can be skipped.

- Document in README

Profile API implementation (#15)

* Profile API implementation
* Update demo apps to show use of profile API
* Update README with Profile API docs

Merge pull request #14 from Optable/cache-targeting

targetingFromCache() and targetingClearCache() APIs

Merge pull request #13 from Optable/6-oeid-auto-identify

Support for auto-identify on newsletter traffic

Update access token for jitpack priv repo

Update access token for jitpack priv repo

Release tag v0.2.4