use connection_string as database configuration instead of a hash

src/db/connection.cr

@@ -1,8 +1,8 @@
 module DB
   abstract class Connection
-    getter options
+    getter connection_string
 
-    def initialize(@options)
+    def initialize(@connection_string)
       @closed = false
     end
 

src/db/database.cr

@@ -6,10 +6,10 @@ module DB
   # It should be created from DB module. See `DB.open`.
   class Database
     getter driver_class
-    getter options
+    getter connection_string
 
-    def initialize(@driver_class, @options)
-      @driver = @driver_class.new(@options)
+    def initialize(@driver_class, @connection_string)
+      @driver = @driver_class.new(@connection_string)
       @connection = @driver.build_connection
     end
 

src/db/db.cr

@@ -12,12 +12,12 @@ module DB
     @@drivers.not_nil![name] = klass
   end
 
-  def self.open(name, options)
-    Database.new(driver_class(name), options)
+  def self.open(name, connection_string)
+    Database.new(driver_class(name), connection_string)
   end
 
-  def self.open(name, options, &block)
-    open(name, options).tap do |db|
+  def self.open(name, connection_string, &block)
+    open(name, connection_string).tap do |db|
       yield db
       db.close
     end

src/db/driver.cr

@@ -1,8 +1,8 @@
 module DB
   abstract class Driver
-    getter options
+    getter connection_string
 
-    def initialize(@options)
+    def initialize(@connection_string : String)
     end
 
     abstract def build_connection : Connection