Refactoring for InheritsByReference:
* RowPermissions now use Expressions instead of function delegates; added Func to ServerDom which returns RowPermissions Expression
* RowPermission tests updated to reflect changes
* FilterExpression changed to return expression instead of IQueryable and added function to optimize and execute expression on a given query
* RowPermissions will now optimize its expression before executing it on a query
* FilterExpression tests updated to reflect changes
* Added ReplaceWithReference class for replacing parameters in expression trees
Finished refactoring of RowPermission to expressions and added InheritFrom:
* Added tests for ReplaceWithReference class
* Implemented InheritFrom concept with internal child concepts for Read and Write permissions
* Added tests for InheritFrom
* Additional minor refactoring
Update ChangeLog.md
Code review changes
Merge pull request #32 from sstublic/master

Merging additions to RowPermissions system
Merge branch 'master' of https://github.com/Rhetos/Rhetos
Added RowPermissions write rules (AllowWrite, DenyWrite)
Added tests for write rules
Minor refactoring.
Merge branch 'master' of https://github.com/sstublic/Rhetos

Conflicts:
	CommonConcepts/Plugins/Rhetos.Dsl.DefaultConcepts/Rhetos.Dsl.DefaultConcepts.csproj