Removed top-level solution

Core, mobile and portable should instead be built from their respective
solution files. This avoids problems with nuget package locations
getting messed up between different solutions.
Removed obsolete solution files
Removed obsolete MSTest files
Added support for statically configured permissions
Updated NancyFX. Added framework for authentication
BasicAuth Authentication

Moved BasicAuthAuthenticationProvider to the modules assembly. Added
unit tests to validate basic auth hooked into Nanvy pipeline. Updated
BrightstarBootstrapper to invoke Enable on all authentication providers
in ApplicationStartup
Client now supports credentials in connection string

Added some unit tests for basic authentication with client credentials.
Initial work on support for user credentials

Upgraded dependency nuget packages.
Created a new Asp.NET service endpoint that users SQL membership
provider as a test data source.
Added support for configuring connections as requiring authentication
and prompting user for credentials as needed.
Added support for user credentials to Polaris
Merge branch 'feature/polaris_credentials_support' into develop
Added information about user credentials
Add roles to MembershipUserIdentity.Claims
Documentation on configuring authentication
Updated LINQ to SPARQL unit tests

Now test the CONSTRUCT format used for eager loading entity framework
query results.
Added support for eager loading sorted LINQ results
Support eager-loading LINQ Distinct queries
Support selecting format on ExportJob

Currently only either NQuads or NTriples and only at the StoreWorker API
level. Needs further work to push the API change up to the client level
- and streaming writer implementations for other RDF formats - but the
internals are done.
Support format on ExportJob

Propagated change up to client API level
Merge branch 'develop' into feature/xamarin
Fixes to portable build and initial test code for Android