[extra-02] install and configure junit formatter

With this change it's possible to generate test report that can be used
alongside continuous integration routine.

.gitignore

@@ -1,28 +1,14 @@
-# The directory Mix will write compiled artifacts to.
+# paths
 /_build/
-
-# If you run "mix test --cover", coverage assets end up here.
 /cover/
-
-# The directory Mix downloads your dependencies sources to.
+/report/
 /deps/
-
-# Where 3rd-party dependencies like ExDoc output generated docs.
 /doc/
-
-# Ignore .fetch files in case you like to edit your project deps locally.
 /.fetch
-
-# If the VM crashes, it generates a dump, let's ignore it too.
-erl_crash.dump
-
-# Also ignore archive artifacts (built via "mix archive.build").
-*.ez
-
-# Ignore package tarball (built via "mix hex.build").
-wabanex-*.tar
-
-# Since we are building assets from assets/,
-# we ignore priv/static. You may want to comment
-# this depending on your deployment strategy.
 /priv/static/
+/priv/plts/
+
+# files
+erl_crash.dump
+*.ez
+wabanex-*.tar