doc: minor tweaks to the dispatch documentation.

Thanks go to @ArthurClemens.
Fixes 563.
core: clean shutdown during boot in case of dependency start failures.

Instead of getting a nasty looking:
{"init terminating in do_boot",{{case_clause,{error,{"no such file or directory","xmerl.app"}}},[{zotonic,ensure_started,1},{zotonic,ensure_started,1},{zotonic,start,1},{init,start_it,1},{init,start_em,1}]}}

Give a:
10:14:41.213 [error] Zotonic failed to start application: no such file or directory: xmerl.app
smtp: fix e-mail receive.
core: add support for {skeleton, <skel>} in site config install_modules list.
core: fix indentation in m_config:all/1.
core: Fix for websocket handshake when qs has more than one parameter
Merge branch 'master' of https://github.com/zotonic/zotonic
mod_acl_adminonly: as all users should be equal, i.e. admins, z_acl:is_admin/1 should return true.

And z_acl:is_admin/1 looks at #context.acl being 'admin' for that.
mod_acl_adminonly: fix, set_admin is not exported by z_acl
mod_admin/mod_admin_frontend: made admin more responsive. Added first version of frontend editor based on mod_admin.
mod_admin: fix '&' in doc description as it crashed the doc generation.
mod_admin: fix body top padding for smaller screens.
mod_admin: Make the modal popup in the admin_frontend as wide as in the admin.
mod_menu: use short title; absolute positioning of item buttons.
mod_admin_frontend: minor textual changes, add dutch translation
mod_menu: show warning when a resource is unpublished.
mod_admin/mod_menu: added option so pass tab to connect/new dialog.
mod_admin_frontend: set default connect tab to 'new'
mod_admin_frontend: preselect the 'text' category for page linking.
mod_admin: make the logon more responsive (header row-fluid; some styling)
core: increase the pivot poll batch

This speeds up reindexing of big websites