Fixed #42, make fetch size configurable

Was hard coded to 1024 bytes which meant that larger messages were
unconsumable since they would always get split causing the consumer to
stop.

It would probably be best to automatically retry truncated messages with
a larger request size so you don't have to know your max message size
ahead of time
Auto-adjusting consumer fetch size

Related to #42

Adds new ConsumerFetchSizeTooSmall exception that is thrown when
`_decode_message_set_iter` gets a BufferUnderflowError but has not yet
yielded a message

In this event, SimpleConsumer will increase the fetch size by 1.5 and
continue the fetching loop while _not_ increasing the offset (basically
just retries the request with a larger fetch size)

Once the consumer fetch size has been increased, it will remain
increased while SimpleConsumer fetches from that partition
Documenting new behavior in CHANGES.md
allow a client id to be passed to the client
Merge pull request #45 from quixey/allow-client-id

Allow a client id to be passed to the client

+1 thanks, @jimjh
Fix #44 Add missing exception class

Also move the exceptions to common instead of util
Update README.md

correct typo in readme example
Merge pull request #47 from StevenLeRoux/master

Update README.md
Update README.md

Small fixes in ## Multiprocess consumer example.
Merge pull request #48 from StevenLeRoux/master

Update README.md
import bufferunderflow error
Merge pull request #49 from jimjh/import-buffer-underflow-error

import bufferunderflow error
add .travis.yml
Merge pull request #53 from jimjh/testing

Enable continuous integration with travis-ci.
Adding git-submodule update to Travis YML file

Hopefully this commit will trigger a build on TravisCI
update README.md to link to travis-ci's build page
Merge pull request #54 from jimjh/patch-1

update README.md to link to travis-ci's build page
Adding a POWERED-BY.md file to people to give us props
Update POWERED-BY.md

Apparently GitHub flavored markdown doesn't fully work in md files? (@mumrah didn't auto-link)
Updating authors, thanks to all the contributors!

Also testing out this -> [skip ci]