Define the deployment descriptors and update ENV variables names

[VincenzoFerme]

Define the deployment descriptor and update ENV variables names once the template is defined in benchflow/collectors#38

[VincenzoFerme]

@Cerfoglg Document here the design on which #19 is based on.

[Cerfoglg]

@VincenzoFerme

The env variables for the monitors:

Mysql monitor:
MYSQL_DB_NAME: name of the mysql database
MYSQL_HOST: mysql host
MYSQL_PORT: port of mysql
MYSQL_USER: user to connect with
MYSQL_USER_PASSWORD: password of the user
BENCHFLOW_CONTAINER_NAME: name of the container
BENCHFLOW_MONITOR_NAME: name of the monitor

Cpu monitor:
CONTAINERS: containers to monitor, coma separated list
BENCHFLOW_CONTAINER_NAME: name of the container
BENCHFLOW_MONITOR_NAME: name of the monitor

[VincenzoFerme]

@Cerfoglg missing the documentation about the deployment descriptor