Fix detection of MIME type in message_parse()

Be careful, content-type may contain tricky content like in the
following example so test the MIME type with startswith()

Content-Type: multipart/related;
  boundary="_004_3f1e4da175f349248b8d43cdeb9866f1AMSPR06MB343eurprd06pro_";
  type="text/html"
[FIX] base: security, group settings is authorized to alter ir.config_parameter
[FIX] base: security, do not override basic ir_config_paramter ACL
Merge pull request #286 from jbq/bugfix

[FIX] mail: detection of MIME type

When parsing the mail headers, the content-type may has a 'type' attribute for Multipart/Related  objects (rfc2387).
Previous check would match on attached files of type text instead of real `content-type: text/`.
[FIX] calendar: avoid double popup, opw 606297

Some browsers (e.g. chrome) trigger onEmptyClick as well as
onBeforeLightbox during drag&drop which calls two slow_create
calls (and two popups). Workaround to kill the second one.
[FIX] delivery: allow to add delivery method in quotation if quotation in quotation sent stage

opw-607920
[FIX] sale: keep customer reference in grouped invoice (opw 606523)
[FIX] stock: use correct vals in grouped invoice (opw 606535)

When creating a grouped invoice, the invoice_vals value is used to create the invoice line.
The value was not reset for grouped invoice and we reused the values of previous line.
[FIX] kanban: avoid wrong placement of button on ie9

On ie9, the 'read more' button in kanban view was placed in the middle of the window instead of the bottom
[FIX] point_of_sale: correct call to default value

The default value should be called with a lambda otherwise the payment_date is set to the date the server was started (opw 606715)
uninstall: avoid errors during uninstall

When uninstalling a module, remove the ir.model.constraint after removing the non-model records and before fields and model definition.
Without this fix, some constraint would be removed too early allowing to have broken relations and data left from removed module.
[FIX] web: many2many field handle "no_create" option
[FIX] project_timesheet: don't trigger write if there is nothing to write

Triggering an empty write could break constraint (can not update past timesheet) (opw 606963)
[FIX] document_page: allow other users than administrator to create menu to a static page

User should be at least have Configuration settings group to be allowed to create actions. Basic document page users do not have this rights, therefore we temporary give superuser_id to create the action

This is related to rev 133c5033a092845e462b894c0d7739191480c709
[IMP] stock: when checking the state of the product, do not recompute the quantity on every move but only the one currently browsing (optiomisation)
[FIX] ir_cron: use the same search criteria as when listing job to excecyte when acquiring the ock on the job before its execution to prevent running already executed job

Backport of fix made in trunk
[FIX] orm: do not resize unlimited char fields
[FIX] Fixes #256: show the deliveries button on POs in almost ever state, so users have an apportunity to guess why a PO is in exception.