adding env var for base dir to vagrantfile

vagrant/release/dosa/devstack/Vagrantfile

 MEMORY = 2048
 CPU_COUNT = 2
+edx_platform_mount_dir = "cs_comments_service"
+forum_mount_dir = "edx-platform"
+
+if ENV['VAGRANT_MOUNT_BASE']
+
+  edx_platform_mount_dir = ENV['VAGRANT_MOUNT_BASE'] + "/" + forum_mount_dir
+  forum_mount_dir = ENV['VAGRANT_MOUNT_BASE'] + "/" + edx_platform_mount_dir
+
+end
 
 Vagrant.configure("2") do |config|
 
@@ -11,8 +20,8 @@ Vagrant.configure("2") do |config|
   config.vm.network :forwarded_port, guest: 8001, host: 8001
   config.vm.network :forwarded_port, guest: 4567, host: 4567
 
-  config.vm.synced_folder "edx-platform", "/edx/app/edxapp/edx-platform", :create => true, nfs: true
-  config.vm.synced_folder "cs_comments_service", "/edx/app/forum/cs_comments_service", :create => true, nfs: true
+  config.vm.synced_folder "#{edx_platform_mount_dir}", "/edx/app/edxapp/edx-platform", :create => true, nfs: true
+  config.vm.synced_folder "#{forum_mount_dir}", "/edx/app/forum/cs_comments_service", :create => true, nfs: true
 
   config.hostsupdater.aliases = ["preview.localhost"]
 
@@ -20,10 +29,14 @@ Vagrant.configure("2") do |config|
     vb.customize ["modifyvm", :id, "--memory", MEMORY.to_s]
     vb.customize ["modifyvm", :id, "--cpus", CPU_COUNT.to_s]
   end
-
+  
+  edxapp_version = "master"
+  forum_version = "master"
   config.vm.provision :ansible do |ansible|
     ansible.playbook = "../../../../playbooks/vagrant-devstack.yml"
     ansible.inventory_path = "../../../../playbooks/vagrant/inventory.ini"
+    ansible.tags = "deploy"
     ansible.verbose = "extra"
   end
+
 end