Read bytes when fetching or uid_fetching. (workaround, do not merge!)

[vandenoever]

This returns raw bytes for each result as well as the id. This was previously #33

This is a first version of this patch. It {c,sh}ould have more error checking.

I've checked this patch with DavMail, an IMAP proxy.

This patch was rejected before but until there is a better patch, this one is useful when one wants to have structured responses. I'm using this personally, so I'm just opening this patch so people that also need this functionality now can use it.

The real fix should come in #28

[coveralls]

Coverage decreased (-1.2%) to 61.23% when pulling 4ca1d15 on vandenoever:fetch into 542ee15 on mattnenterprise:master.

[vandenoever]

Since rust-imap moved to imap-proto, this pull request is no longer relevant.
Instead of this patch, one can use run_command_and_read_response and then parse with imap-proto.