Android-SDK - 3.5.0

## 3.5.0
March 13th, 2020

This release includes an enhancement of SDK initialization API to enable SDK updated on cached datafile change. It also fixes known bugs.

### New Features
* Add an option for **synchronous** initialization to enable SDK immediately updated when a new datafile is cached. Unless this feature is enabled, by default, the cached datafile will be used only when the SDK re-starts in the next session. Note that this option is for **synchronous** initialization only. ([#318](

// enable SDK update when a new datafile is cached
optimizelyManager.initialize(context, R.raw.datafile, true, true)

// by default, this feature is disabled
optimizelyManager.initialize(context, R.raw.datafile)

### Bug Fixes
* When datafile download fails or receives 304, the SDK loads a datafile from cache. This loading process is moved to a background thread. ([#321](