Allow instance mods if only osparams are given
Allow instance mods if only osparams are given

osparams are now recognized as changes, so changing only those without
other changes works too now.

Signed-off-by: Thomas Thrainer <98bdeac947eb8ca18146e9ce7f092788ec242cd1@google.com>
Reviewed-by: Helga Velroyen <2d0126b1ec6f9ec5cbec4a7012aa14faeaef10f5@google.com>

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