updated dependencies version to be compatible with XamarinStudio
Update readme.

Add new addin repository url for Xamarin Studio.
Update app version to 4.0 for addins.monodevelop.com
Update to NuGet 2.5
Add file conflict dialog.
Remove unused code.
Support NuGet packages containing MSBuild targets and props files.

MSBuild props files are added to the top of the project whilst
targets files are added to the end.
Support pre-release NuGet packages.
Add credential provider for NuGet feeds.

Only supports credentials stored in NuGet.config under
the user's profile:

nuget sources update -name MyFeed -username user -password pass
Fix duplicate assembly references when installing NuGet.

References to assemblies in a project that use the qualified assembly name, such as:
"NUnit.Framework, Version=2.6.2.0, Culture=neutral, PublicKeyToken=8cc8392e8503e009"
were not being removed and re-added when installing a NuGet package that included
that reference.
Add Update All button to Manage Packages dialog.
Add Update All button to Manage Packages dialog.
Support updating all NuGet packages in solution from dialog
Refactor UpdatedPackagesViewModel.
Fix updated packages not being shown in dialog.

Updated packages were not being displayed in the
Manage Packages dialog when the solution was selected
and two or more projects had the same NuGet packages but
different versions.

http://nuget.codeplex.com/workitem/3034
Fix Include Prerelease checkbox missing from Updates tab.
Clear dialog error messages when updating all NuGet packages.
Update installed NuGet packages after updating all packages in dialog.
Refresh updated NuGet packages after updating in dialog.
Fix exception when saving NuGet.config settings.

InvalidOperationException thrown by Mono 2.10.9:
    This XmlWriter does not accept Text at this state Prolog.

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.InvalidOperationException: This XmlWriter does not accept Text at this state Prolog.
  at System.Xml.XmlTextWriter.ShiftStateContent (System.String occured, Boolean allowAttribute)
  at System.Xml.XmlTextWriter.WriteString (System.String text)
  at System.Xml.DefaultXmlWriter.WriteString (System.String text)
  at System.Xml.Linq.XText.WriteTo (System.Xml.XmlWriter w)
  at System.Xml.Linq.XDocument.WriteTo (System.Xml.XmlWriter w)
  at System.Xml.Linq.XDocument.Save (System.Xml.XmlWriter w)
  at System.Xml.Linq.XDocument.Save (System.IO.Stream stream, SaveOptions options)
  at System.Xml.Linq.XDocument.Save (System.IO.Stream stream)
  at NuGet.PhysicalFileSystem.AddFileCore (System.String path, System.Action`1 writeToStream)
  at NuGet.PhysicalFileSystem.AddFile (System.String path, System.Action`1 writeToStream)
  at NuGet.Settings.Save ()
  at NuGet.Settings.SetValueInternal (System.Xml.Linq.XElement sectionElement, System.String key, System.String value)
  at NuGet.Settings.SetValue (System.String section, System.String key, System.String value)
  at NuGet.PackageRestoreConsent.set_IsGrantedInSettings (Boolean value)

Workaround is to load the settings without preserving whitespace.

Looks like this has been fixed in mono 3.0.12
https://bugzilla.xamarin.com/show_bug.cgi?id=3231
https://github.com/mono/mono/commit/2927d27304ae9d2ea2e40f9277055bcfde2bb554