proxy/meta2: container properties need review

[jkasarherou]

We currently have something like this for meta2 containers properties:

{
"schema_version": "1.8",
"sys.account": "test",
"sys.m2.ctime": "1435593742",
"sys.m2.init": "1",
"sys.m2.usage": "-598",
"sys.m2.version": "10",
"sys.name": "AEA6D3A7C15F0E5C3E61A68DB8DD729637A9890C67DC2ED41BAFCD1BFCA1A12A.1",
"sys.ns": "NS",
"sys.type": "meta2",
"sys.user.name": "1",
"version:main.admin": "1:0",
"version:main.alias_v2": "11:0",
"version:main.chunk_v2": "11:0",
"version:main.content_header_v2": "11:0",
"version:main.content_v2": "11:0",
"version:main.properties_v2": "1:0"
}

Looks like it could use a refactoring/cleaning.

[jkasarherou]

{
    "schema_version": "1.8",
    "sys.account": "myaccount",
    "sys.m2.ctime": "1456235615715844",
    "sys.m2.init": "1",
    "sys.m2.usage": "752522",
    "sys.m2.version": "1",
    "sys.name": "EA1562F469399581D0BE45E9FCB906BF650E170A65690116A4110D92271E3701.1",
    "sys.ns": "NS",
    "sys.type": "meta2",
    "sys.user.name": "1",
    "version:main.admin": "1:0",
    "version:main.aliases": "1:0",
    "version:main.chunks": "1:0",
    "version:main.contents": "1:0",
    "version:main.properties": "1:0"
}

"schema_version": "1.8" deprecated
but otherwise this is better