Merge branch 'dont-litter-workdir' into 'master'

Don't litter workdir when running tests

See merge request picodata/brod/tarantool-module!42

Author: gmoshkin

tests/run_tests.lua

@@ -1,11 +1,18 @@
 #!/usr/bin/env tarantool
 
-fiber = require('fiber')
+local fio = require('fio')
+local fiber = require('fiber')
+
+local tmpdir = fio.tempdir()
 
 box.cfg{
     listen = 3301,
+    wal_mode = 'none',
+    memtx_dir = tmpdir,
 }
 
+fio.rmtree(tmpdir)
+
 -- Init test database
 box.once('bootstrap_tests', function()
     box.schema.user.create('test_user', { password = 'password' })