Solve an edge-case of syntax highlighting in README.md

In my vim-setup, the underscore in `create_resources` leads to
rendering everything in italics after that. Wrapping it in backticks
solves this in the editor and also looks better when rendered as HTML.
Merge pull request #152 from kronn/patch-1

Solve an edge-case of syntax highlighting in README.md
Fix tests for Puppet 3.0 target
Fix issue with twice declaration of Database_user resource
Merge pull request #154 from Paulche/master

Fix issue with redeclaration of database_user via mysql::db
Restrict the versions and add 3.1

'~> 2.6' will match 2.7.x.
Merge pull request #155 from richardc/patch-1

Restrict the versions and add 3.1
fix mocha deprecation warnings
Merge pull request #156 from mattr-/fix-mocha-warnings

fix mocha deprecation warnings
Adding php bindings to readme
Merge pull request #158 from ke4qqq/patch-1

Adding php bindings to readme