PHP : Disable Strict mode reporting, Enable libxml in php. Warning : if libz*-dev is installed, php won't compile

As slapos.libnetworkcache does not depend on M2Crypto anymore, but on
existence of openssl in PATH drop building of this library and just
tweak slapgrid-sr environment to allow find the openssl in PATH.

http://git.erp5.org/gitweb/slapos.git/commitdiff/2edb5d390f3f8a8fb2ca2deeb355aa1eb6498796

Additionaly use template engine and separate environment definition to own
section.

Other tools will have possiblity to read runtime, separated, environment of
SlapOS node.

This is following the idea of providing isolation from operating system
environment.