Remove fmt from environment header (#78)

Summary:
Pull Request resolved: #78

This makes it so we don't have to package fmt headers with oss deploy release.

Reviewed By: PaliC

Differential Revision: D37408294

fbshipit-source-id: bc11ae12f37b08239a054e087d286b3070686f3d

Author: s4ayub

multipy/runtime/environment.h

@@ -5,7 +5,6 @@
 // LICENSE file in the root directory of this source tree.
 
 #pragma once
-#include <fmt/format.h>
 #include <fstream>
 #include <string>
 #include "Exception.h"
@@ -62,7 +61,7 @@ class Environment {
     setupZippedPythonModules(pythonAppDir);
   }
   virtual ~Environment() {
-    auto rmCmd = fmt::format("rm -rf {}", extraPythonLibrariesDir_);
+    auto rmCmd = "rm -rf " + extraPythonLibrariesDir_;
     system(rmCmd.c_str());
   }
   virtual void configureInterpreter(Interpreter* interp) = 0;