Add vnf packages RestFul APIs

Implemented following APIs:-

* GET    /vnf_packages
* POST   /vnf_packages/
* GET    /vnf_packages/{vnfPkgId}
* DELETE /vnf_packages/{vnfPkgId}
* PUT    /vnf_packages/{vnfPkgId}/package_content
* POST   /vnf_packages/{vnfPkgId}/package_content/upload_from_uri

Partial-Implements: blueprint tosca-csar-mgmt-driver

Depends-On: If8155399df12a96cb86631dfa22eaca7a5a8d398

Co-Author: Neha Alhat <neha.alhat@nttdata.com>
Change-Id: Id3b4812e24a1ed84fe94429e074f96ae11530517

lower-constraints.txt

@@ -33,6 +33,7 @@ fixtures==3.0.0
 flake8==2.5.5
 future==0.16.0
 futurist==1.6.0
+glance-store==0.26.1
 google-auth==1.4.1
 greenlet==0.4.13
 hacking==0.12.0
@@ -151,7 +152,7 @@ tenacity==4.9.0
 testresources==2.0.1
 testscenarios==0.5.0
 testtools==2.2.0
-tosca-parser==0.8.1
+tosca-parser==1.6.0
 traceback2==1.4.0
 unittest2==1.1.0
 urllib3==1.22