* Enable VNF vendors to customize configuration methods
for applications via MgmtDriver
* Load LCM interface from vnfd file
* Call LCM methods from vnflcm_driver
* Fix unitentional mgmt_calls in vnflcm_driver._scale_vnf_pre
Note:
* For UT, sqlalchemy is used, which calls functions in pymysql.py,
so the dependency module PyMySQL needs to be added.
* The previous implementation of ``cfg.CONF.tacker.infra_driver``
depends on the default config in legacy ``VNFMPlugin`` class in
tacker/vnfm/plugin.py, so we need to fix this here.
* Due to drop unitentional mgmt_calls, it makes compatibility breakage
for some scale actions calls and third party driver support. This
backward incompatibility was decided to keep since it is not long
time since last change(Victoria release)
Change-Id: Ib4ad3eb9e0a84d1a5e807d2e6004e6b2c02bf3cf
f88022cdc2