Simplify the cstats initializer
Simplify the cstats initializer

Since all values are initialized to zero, the exact ordering is not
important and thus we can use the positional mode for simpler code.

The patch also adds docstrings to the cstats functions.

leshchevds/ganeti,apyrgio/snf-ganeti,apyrgio/snf-ganeti,ganeti/ganeti,mbakke/ganeti,grnet/snf-ganeti,bitemyapp/ganeti,yiannist/ganeti,ganeti/ganeti,dimara/ganeti,yiannist/ganeti,bitemyapp/ganeti,grnet/snf-ganeti,ganeti-github-testing/ganeti-test-1,yiannist/ganeti,andir/ganeti,leshchevds/ganeti,dimara/ganeti,apyrgio/ganeti,mbakke/ganeti,apyrgio/ganeti,andir/ganeti,leshchevds/ganeti,onponomarev/ganeti,ganeti/ganeti,onponomarev/ganeti,mbakke/ganeti,ganeti-github-testing/ganeti-test-1,andir/ganeti