Optimize execution duration for rspec specs

* Use in memory sqlite database for test environment
* Monkey patch BCrypt default cost factor
* Clean spec/spec_helper.rb

config/database.yml

@@ -11,7 +11,7 @@ development:
 # Do not set this db to the same as development or production.
 test: &test
   adapter: sqlite3
-  database: db/test.sqlite3
+  database: ':memory:'
   pool: 5
   timeout: 5000
 
@@ -22,4 +22,4 @@ production:
   timeout: 5000
 
 cucumber:
-  <<: *test
+  <<: *test