build: fastlane setup

- Adds a configuration called 'Development' to the project, which uses
  manual signing

- Changes the 'Release' configuration to use manual signing

- Adds support for fastlane automation.
  This commit adds 2 lanes:

  - 'test' uses scan to build and run unit tests on the client

  - 'build' unlocks the system's keychain, uses match to sync the
    development certificate and provisioning profile with a private git
    repo, then uses gym to build the development configuration of the
    xcode project

- Adds a .gitignore to Ring/fastlane for undesired fastlane related files

Change-Id: I1bc0eb8cfa20cc536c297ba7ae14292cc66e1d96
diff --git a/Ring/fastlane/metadata/review_information/demo_user.txt b/Ring/fastlane/metadata/review_information/demo_user.txt
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/Ring/fastlane/metadata/review_information/demo_user.txt
@@ -0,0 +1 @@
+