Merge pull request #73 from jeffma/master

repair clack.request::parameters->plist decode params error
Fix Hunchentoot Handler not to ignore Accept header.
Add a keyword arg 'use-cl-debugger' to 'clackup'. If it's NIL, it'll use clack-errors.
Add a keyword arg 'watch' to 'clackup'.
Change the rule of version numbers.

They are used to be decided from the release date (ex. 2012-08 -> v12.08.0).
But it causes a warning "Invalid :version specifier" of ASDF.

This is changing the rule of version numbers of all Clack asd files.
Their versions are roughly decided from their history.
Drop 'w' from my name.
Stop binding *clack-output* & *clack-error-output* when loading clack.
Add 'wrap' for 'function's.
Add Clack.Middleware.Accesslog.
Fix computing of content-length in Clack.Middleware.Accesslog.
Delete a needless importing.
Add Clack.Middleware.(Backtrace|Accesslog) to README.
Add Clack.Session.Store.Dbi (contrib).
Fix style-warnings saying 'Implicitly creating a generic function'.
Change the timezone offset in a cookie from +0000 to GMT because Drakma cannot parse it.
Load watching files including those dependencies.
Use bt:*supports-threads-p* as the default value for use-thread flag of file-watcher.
Doesn't make a thread in Clack.Handler.Fcgi if the impl doesn't support threads.
Prevent "Connection reset by peer" error from Hunchentoot.
Check :shelly feature in execution-time.