In the case of hellorina SR, the following section generated invalid command:

[proxy]
command-line = {{ python_location }}/bin/python2.7 {{ rina_proxy }} ${server:instance-guid} ${:ipv6} ${:port}
...

This value can be used as a unique identifier within the cloud.
It was already available for the requesting partition ('request' recipe).

/reviewed-on nexedi/slapos!101

/reviewed-by: TrustMe

Add a class SlapConfigParser which overrite ConfigParser.write method to fix parse problem when
configuration like:
[section]
foo += bar

is included in buildout file. softwaretype recipe will generate
buildout file with foo + = bar because ConfigParser doesn't reconize +=
delimiter and read key as "foo +", value as "bar".
Then ConfigParser.write method generate

[section]
foo + = bar
...

This is invalid with buildout version 2

/reviewed-on !100