Merge pull request #88 from AnthonySteele/cachetests

Looks good to me!
automated package build and version number increment to 8
UsingCache needs to be on the IFluentApi interface
automated package build and version number increment to 9
Two updates to the powershell build nuget package script
1) We can get the last package version from nuget with "nuget list SevenDigital.Api.Wrapper"
So we don't need to store it in a file (and do those annoying automated git commits).
2) make some methods with "CmdletBinding() param()" for safety as per http://stackoverflow.com/questions/16506899/powershell-is-ignoring-expression-after-function-call