Add External Interface NBI project into OOM

Add External Interface NBI project into OOM

NBI (North Bound Interface) is one of the new project added for Beijing
release.

Features added
==============

MongoDB common chart
--------------------

Ability to start a mongo container, with a chart consistent with other
common charts (readiness, liveness, persistence, resources, nfs,
service, ...).

Specific configuration:
  * name of the db to create if needed

NBI chart
---------

Ability to start a mariadb container, with a chart consistent with other
common charts (readiness, liveness, persistence, resources, nfs,
service, ...).

Specific configuration:
  * name of the db to create if needed
  * name of the user that has access to the db
  * password of the user that has access to the db
  * root password of the database

Ability to start a NBI container, with a chart consistent with other
common charts (readiness, liveness, persistence, resources, nfs,
service, ...).

Specific configuration:
  * log level
  * cloudOwner
  * ecompInstanceId
  * openStackRegion
  * openStackServiceTenantName
  * sdc_authorization
  * aai_authorization
  * so_authorization

ONAP chart
----------

Added a requirement on NBI chart, possibility to enable/disable and
configuration to push to the chart.

Current Status
==============

- [*] adding a common chart for mongodb
- [*] make mongo chart compiling
- [*] testing the mongodb common role
- [*] creating a mariadb chart inside nbi helm
- [*] testing the mariadb chart
- [*] make mariadb chart compiling
- [*] make nbi use these charts
- [*] make nbi chart compiling
- [*] test the whole solution
- [*] create a service for nbi

Change-Id: I8dd3e79768c83b1553a05c892cf418f840931255
Issue-ID: EXTAPI-54
Signed-off-by: Sylvain Desbureaux <sylvain.desbureaux@orange.com>