Fix problem with account selector

When sending a message, the account selector was ignoring
the account set by the before-edit hook.  Fix this
by running the hook before setting up the account selector.
Added simple auto-completion to search prompt

Currently, label completions for all labels are supported, as well as
these keywords: from, to, after, date, before, date, limit, AND, OR, NOT
Merge #16: Fix YAML regression in 1.9

Squashed commit of the following:

commit a26b99c64e2da4115ea47606ae8b66f0b008b002
Author: Whyme Lyu <callme5long@gmail.com>
Date:   Tue Mar 26 23:03:50 2013 +0800

    Ensure Syck is used.

    In the long run we'd better drop Syck in favor of Psych

commit a99a2b244063c2088d91688f667ee68f05f24df0
Author: Whyme Lyu <callme5long@gmail.com>
Date:   Tue Mar 26 23:03:25 2013 +0800

    A regression test for YAMLing in 1.9
sup-config: call to_s() on user input

Highline seems to use its own string wrapper for data entered by the
user. When converting to yaml, the value is annotated with
'!str:HighLine::String', which leads to errors when starting sup or
sup-sync.

Fixes issue #28
Merge pull request #29 from ericweikl/sup-config-bug28

sup-config: call to_s() on user input
Merge pull request #27 from ericweikl/develop

Add auto-completion to search prompt
Merge and close #24: Remove old and abandoned Ditz bug system and bugs
Allow builds on 2.0 fail for now
s/Config/RbConfig for less warnings
Explicitly require 'rbconfig' before using it
Merge pull request #31 from 5long/allow-2.0-builds-fail

Allow builds on 2.0 fail for now
Merge pull request #32 from 5long/remove-rbconfig-warning

Remove rbconfig warning
Merge branch 'sup-heliotrope/develop' into maildir-sync