The incorrect index error will only happen
if an token is locked down to a specific index(es).

Specify the max number of retries when configuring
a logger. The maximum backoff (time between retries)
is capped at 2 minutes.

Also updated tests.

When this many events are in the contextQueue,
flush() will be called.

TODO:
- Make some decisions about middleware
- Update remaining examples
- Add a few timer tests for 100% coverage

- Added ability to have custom event formatter
- Context no longer has config or requestOptions
- If !autoflush and any batching settings, throw an error
- Simplified logic in many places
- Added several util functions
- Updated tests
- Clarified the basic.js example

All batch settings will be ignored when they are <= 0.

Added remaining tests for utils

We have collectively decided that this feature
does not provide enough value at this time.

This change optimizes the flush() function
since events will only be serialized once
after passed to send().

Without middleware, we no longer need
to store un-serialized objects.

To disable autoFlush behavior, set all
batching settings to 0. It is still
enabled by default - flushing events
1 by 1. Modify this behavior through
the config object.