Use a safer random name for containers (closes GH-192)

if the same vagrantfile is up'd in the same second in the same basedir
this caused a conflict

CHANGELOG.md

@@ -4,6 +4,10 @@ FEATURES:
 
   - Support for naming containers from Vagrantfiles [#132](https://github.com/fgrehm/vagrant-lxc/issues/132)
 
+IMPROVEMENTS:
+
+  - Use a safer random name for containers [#152](https://github.com/fgrehm/vagrant-lxc/issues/152)
+
 BUG FIXES:
 
   - Properly detect if lxc is installed on hosts that do not have `lxc-version` on their paths [#186](https://github.com/fgrehm/vagrant-lxc/issues/186)

lib/vagrant-lxc/action/create.rb

@@ -17,7 +17,9 @@ module Vagrant
             else
               container_name = "#{env[:root_path].basename}_#{env[:machine].name}"
               container_name.gsub!(/[^-a-z0-9_]/i, "")
-              container_name << "-#{Time.now.to_i}"
+              # milliseconds + random number suffix to allow for simultaneous
+              # `vagrant up` of the same box in different dirs
+              container_name << "_#{(Time.now.to_f * 1000.0).to_i}_#{rand(100000)}"
           end
 
           env[:machine].provider.driver.create(