pkgin: use module.run_command to run stuff

This also fixes an issue where some console output for packages I was
installing was creating invalid JSON because it contained single-quotes.

library/pkgin

@@ -63,7 +63,7 @@ def query_package(module, name, state="installed"):
 
     if state == "installed":
 
-        rc = os.system("%s list | grep ^%s" % (PKGIN_PATH, name))
+        (rc, stdout, stderr) = module.run_command("%s list | grep ^%s" % (PKGIN_PATH, name))
 
         if rc == 0:
             return True
@@ -80,7 +80,7 @@ def remove_packages(module, packages):
         if not query_package(module, package):
             continue
 
-        rc = os.system("%s -y remove %s" % (PKGIN_PATH, package))
+        module.run_command("%s -y remove %s" % (PKGIN_PATH, package))
 
         if query_package(module, package):
             module.fail_json(msg="failed to remove %s" % (package))
@@ -102,7 +102,7 @@ def install_packages(module, packages):
         if query_package(module, package):
             continue
 
-        rc = os.system("%s -y install %s" % (PKGIN_PATH, package))
+        module.run_command("%s -y install %s" % (PKGIN_PATH, package))
 
         if not query_package(module, package):
             module.fail_json(msg="failed to install %s" % (package))