bump metasploit_data_models, speedup workspace deletion

Author: Brent Cook

Gemfile.lock

@@ -197,7 +197,7 @@ GEM
       activesupport (~> 4.2.6)
       railties (~> 4.2.6)
     metasploit-payloads (1.2.33)
-    metasploit_data_models (2.0.14)
+    metasploit_data_models (2.0.15)
       activerecord (~> 4.2.6)
       activesupport (~> 4.2.6)
       arel-helpers