* XmlHelper.cs: Added an XmlHelper extension class to multipplatform

* DatabaseContext.cs: Ammend mysql disclaimer for unix systems

* PlatformHelper.cs: Added is IsMono property to multiplatform helper

* MySqlSyntaxProvider.cs: Disable filesystem casing check for unix /
  linux systems - overly restrictive. Let's see if we can still get
  mileage out of the orm

* Umbraco.Core.csproj: Added XmlHelper to multiplatform

* Umbraco.Web.UI.csproj: Add System.Web.Entity as external dll

* ClientDependency.config: autoupdate - commit for now

* DefaultUser.cs:
* FilePermissions.cs: casing correction

* p.aspx.cs: switch to using Current() XmlHelper Multiplatform
  extension to deal with XPathNodeIterator mono initialisation.