Partial logging fix

[anushjay]

• Initialize partial logging buffer with default values
• Send messages when the partial flag is unset or partial buffer reaches max capacity or timer expires
• Reset buffer when a message has been sent successfully.

[sharonx]

I suggest that we change reference to partial to temp

To me the logic is:

for each message the reader reads:
    append it to a temporary buffer
    if partial == False or Timer is up or Size limit is exceeded:
        flush temp buffer

[anushjay]

@chenziliang Made changes after your review.

[anushjay]

@sharonx Made changes as per your request.

[anushjay]

@chenziliang @sharonx Made changes so messages are verified for sending before adding to buffer. Please review when you get a chance. All tests are passing.

[sharonx]

We can merge the PR first. However, I'd like to see unit tests for tempBuffer.

[chenziliang]

It is way cleaner right now. LGTM. Thanks !