[repository] #1460066: backport datafeed cube as cubicweb source
* add some attributes to CWSource to handle this kind of source
(not natural to put everything in 'config' string). Adding a CWSource
subclass has been attempted then rollbacked because it adds pain
to handle multi-sources planning and it introduce an ambiguity on
a generic relation (cw_source), which may be a penalty in multiple
case
* data feed sources are a new kind of source, namely 'copy based',
which have no effect on the query planner
* a data feed source is associated to a list of url and a parser (appobjects
in the 'parsers' registry
* entities imported by a data feed have cwuri set to their url on the distant
site, their cw_source relation point to the data feed source, though their
source stored in the entities table (returned by cw_metainformation) is their
physical source, hence 'system'
dn: dc=cubicweb,dc=test
structuralObjectClass: organization
objectClass: dcObject
objectClass: organization
o: cubicweb
dc: cubicweb
dn: ou=People,dc=cubicweb,dc=test
objectClass: organizationalUnit
ou: People
structuralObjectClass: organizationalUnit
dn: uid=syt,ou=People,dc=cubicweb,dc=test
loginShell: /bin/bash
objectClass: inetOrgPerson
objectClass: posixAccount
objectClass: top
objectClass: shadowAccount
structuralObjectClass: inetOrgPerson
cn: Sylvain Thenault
sn: Thenault
shadowMax: 99999
gidNumber: 1004
uid: syt
homeDirectory: /home/syt
shadowFlag: 134538764
uidNumber: 1004
givenName: Sylvain
telephoneNumber: 106
displayName: sthenault
gecos: Sylvain Thenault
mail: sylvain.thenault@logilab.fr
mail: syt@logilab.fr
dn: uid=adim,ou=People,dc=cubicweb,dc=test
loginShell: /bin/bash
objectClass: inetOrgPerson
objectClass: posixAccount
objectClass: top
objectClass: shadowAccount
cn: Adrien Di Mascio
sn: Di Mascio
shadowMax: 99999
gidNumber: 1006
uid: adim
homeDirectory: /home/adim
uidNumber: 1006
structuralObjectClass: inetOrgPerson
givenName: Adrien
telephoneNumber: 109
displayName: adimascio
gecos: Adrien Di Mascio
mail: adim@logilab.fr
mail: adrien.dimascio@logilab.fr