[ADD] views documentation

addons/email_template/wizard/email_template_preview_view.xml

addons/hr_payroll/hr_payroll_view.xml

addons/purchase/purchase_view.xml

addons/survey/wizard/survey_email_compose_message.xml

addons/web/static/src/css/base.sass

addons/website_quote/views/website_quotation_backend.xml

doc/reference/data.rst

doc/reference/javascript.rst

doc/reference/qweb.rst

doc/reference/views.rst

openerp/addons/base/ir/ir_translation_view.xml

openerp/addons/base/rng/view.rng

openerp/tools/convert.py