Added BasicAuthCredentials
made username and password of BasicAuthCredentials private
removed unnecessary ctors and added some validation
Merge pull request #3 from Gandalis/master

Added BasicAuthCredentials
better null checks for BasicAuthCredentials
querystring: use updated key value, urlencode key
add PCL support, extract X509 support into a separate project
code cosmetics and cleanup after merge
extract isTls logic into Credentials types
extract basic auth into Docker.DotNet.BasicAuth
nuget: 1.1.0-beta, X509=1.0, BasicAuth=1.0
v1.1.0 readme update
nuget: 1.1.0 manifest