Adding support for Entity Framework 6 into MiniProfiler

Although EF6 is currently in Alpha stage, they have made significant changes to bot the underlying injection points as well as the namespaces, requiring a new project (targeting .NET 4.5) to add support.

This pull request adds that project, as well as the needed implementation to inject MiniProfiler into both DbContext and ObjectContext classes. (SqlServer only for now, will probably add SqlCe support also, other providers will hopefully come later as EF6 reaches beta and later RTM).

All that is needed is instead of the old way of calling MiniProfilerEF.Initialize() or using the ObjectContextUtils.CreateObjectContext<MyModel>(conn); you now just need to add the following in the web.config:
```
<configSections>
  <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
  <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
</configSections>
<entityFramework>
  <providers>
    <provider invariantName="System.Data.SqlClient" type="StackExchange.Profiling.Data.EFProfiledSqlClientDbProviderServices, MiniProfiler.EntityFramework6" />
  </providers>
</entityFramework>
```

B.t.w, I seem to be unable to make the commit history on this pull request cleaner, don't know if I'm doing something wrong (I'm a GitHub noob). The files changed are correct though.