[ISSUE #4] Addressing infinite loop and undersized default buffer

[lmnewton]

There might be two separate causes for this and both should be addressed with this PR.

The buffer size in dev mode is set lower than in the docker container. This isn't really necessary as the buffer size is already sufficiently small in the container. I've increased the default to be 8192 to be consistent across run modes. There are already unit tests to consider smaller buffer sizes and those will stay in place but for practical use cases (large log files) undersizing the buffer is a mistake.

The other issue I encountered locally while tuning the default buffer size. There is an edge case where the last line of iteration fits exactly into the buffer. When this happens it's possible for an infinite loop to occur as the last buffer read happens infinitely. This has been addressed with a check if scrollback == buffer_size and unit tests on a new log file that triggers this behaviour.

Closes #4