Added quotation marks for postgresql parameters.

As a new, novice user, I ran into an issue where my postgresql
password contained special characters.  After a brief conversation
with DenSchub on #diaspora, it was noted that while the example
database configuration had quotes added for mysql, but not for
postgresql, and it was suggested this be improved.

closes #7875

Changelog.md

@@ -2,6 +2,7 @@
 
 ## Refactor
 * Remove mention of deprecated `statistic.json` [#7867](https://github.com/diaspora/diaspora/pull/7867)
+* Add quotes in `database.yml.example` to fields that may contain special characters [#7875](https://github.com/diaspora/diaspora/pull/7875)
 
 ## Bug fixes
 * Add compatibility with macOS to `script/configure_bundler` [#7830](https://github.com/diaspora/diaspora/pull/7830)

config/database.yml.example

 postgresql: &postgresql
   adapter: postgresql
-  host: localhost
+  host: "localhost"
   port: 5432
-  username: postgres
-  password:
+  username: "postgres"
+  password: ""
   encoding: unicode
 
 mysql: &mysql