Merge pull request #22 from slav/master

message sender: default guid envelope id is now cast to lower case
Fixed hints for references in SaaS.Domain.Tests
Add support for describe methods to DSL
Use string representation for summary
Override DSL lookup by passing path
remove dsl project, add dsl.exe (lokad-dsl:95c4ce6c16c)
Get rid of the StreamErrors class
Move all stream exceptions closer
add FileDocumentReaderWriter unit test
add unit test for FileDocumentStore
add unit test for MemoryDocumentReaderWriter
add unit test for MemoryDocumentStore
rendered in an abstarct class DocumentReaderWriterTest and DocumentStoreTest
add unit test FileStorageConfigTest
add unit test for FileStorageConfig
add unit test StorageFramesEvil
modify document reader and writer test
add new test for ExtendDocumentWriter(IDocumentWriter) class
add unit test for FileAppendOnlyStore
use using for FileAppendOnlyStore