Issue #240: Unable to edit owners/subscribers

[bug] As the field date_admin and date_subscriber are no longer used but they have NOT NULL constraint, they should be deleted.

wwsympa.fcgi.in: fix calling order for List->new(): should be (list, robot)

WWSympa: Dates in "subscriber option" page are shown in epoch format

Separate namespace for modules providing web interface: Alternative.
Suggested by racke.

Small refactoring: session_table_ttl and anonymous_session_table_ttl parameters aren't overridable by robot context.

Fix bug by change of issue #172 by ikedas

Feature: support for Bcrypt password hashes by mpkut

Deprecate datetime field type in database

[change] pictures_url & pictures_path are no longer may be per-robot parameters.  Because list subdirectories under PICTURESDIR are assumed.

[change] css_url & css_path are no longer may be per-robot parameters.  Because robot subdirectories under CSSDIR are assumed.

Issue #216: Unify scenario names #217 by qosobrin

Use "undef" instead of empty string when calling Sympa::User::password_fingerprint without a previous password hash