Work around BC break in Ruby mongo driver v1.8.4

Fixes #100

CHANGELOG.markdown

@@ -1,3 +1,10 @@
+## v2.3.4
+
+ * [Fix #100][i100] — Work around backwards compatibility break in `mongo` gem 1.8.4 (Ruby backend).
+
+[i100]: https://github.com/bobthecow/genghis/issues/100
+
+
 ## v2.3.3
 
  * [Fix #105][i105] — Fix bug introduced when rendering DB references.

genghis.rb

@@ -530,13 +530,13 @@ def initialize(dsn)
           # name this server something useful
           name = uri.host
 
-          if user = uri.auths.map { |a| a['username'] }.first
+          if user = uri.auths.map { |a| a[:username] || a['username'] }.first
             name = "#{user}@#{name}"
           end
 
           name = "#{name}:#{uri.port}" unless uri.port == 27017
 
-          if db = uri.auths.map { |a| a['db_name'] }.first
+          if db = uri.auths.map { |a| a[:db_name] || a['db_name'] }.first
             unless db == 'admin'
               name = "#{name}/#{db}"
               @db = db

src/rb/genghis/models/server.rb

@@ -16,13 +16,13 @@ def initialize(dsn)
           # name this server something useful
           name = uri.host
 
-          if user = uri.auths.map { |a| a['username'] }.first
+          if user = uri.auths.map { |a| a[:username] || a['username'] }.first
             name = "#{user}@#{name}"
           end
 
           name = "#{name}:#{uri.port}" unless uri.port == 27017
 
-          if db = uri.auths.map { |a| a['db_name'] }.first
+          if db = uri.auths.map { |a| a[:db_name] || a['db_name'] }.first
             unless db == 'admin'
               name = "#{name}/#{db}"
               @db = db