[FIX] hr_recruitment: avoid overriding email_from and email_cc in

[FIX] hr_recruitment: avoid overriding email_from and email_cc in
message_update. This behavior makes sens only in message_new when
setting initial parameter of the applicant, not when somebody sends
an email on the record.
Removed priority change when there is  a 'priority' key in msg; but
this key is not likely to be present in a parsed email.
Removed updated values change due to a mapping of values present in
the email. This code was a copy-and-paste from crm and did not have
any meaning in hr_recruitment.

Also removed unnecessary code in project, project_issue, crm_helpdesk
and crm_claim for the same reasons as for hr_recruitment.

bzr revid: tde@openerp.com-20131104092731-ixasweoy1dbllbb3