CFY-767 modified plugin installer to receive a list of plugins rather than a single one
CFY-767 sending single task for plugin installation for agent worker
CFY-767 removed print line in plugin installer mock
Merge pull request #40 from cloudify-cosmo/feature/CFY-767-plugin-installer-should-receive-a-list-of-plugins

CFY-767 modified plugin installer to receive a list of plugins rather th...