New features and fixes

[REF] attribute-deprecated: Deprecate length class attribute (#86)
[ADD] missing-return
[FIX] manifest-version-format: Support -e manifest-version-format only
[FIX] Whitelist anybox.testing.openerp
[FIX] manifest-version-format: Fix regex to use explicit dot instead …
[FIX] manifest-version-format: Support -e manifest-version-format only
[FIX] missing-import-error: Updating libraries used from requirements.txt but not imported or nested imported from odoo
[IMP] manifest-version-format: Add valid_odoo_versions parameter to force a valid version of odoo in the manifest version
[REF] missing-import-error: Skip test file
[ADD] Support for 10.0 manifest name
[REF] requirements: Update developer version of pylint and astroid