Refactoring and addressing a few issues

<a href='#crh-start'></a><a href='#crh-data-%7B%22processed%22%3A%20%5B%22https%3A//github.com/AzureAD/azure-activedirectory-library-for-dotnet/pull/140%23discussion_r22016192%22%5D%2C%20%22comments%22%3A%20%7B%22Pull%20edf2ed80b2caacb51e316d78126d122fc9c0a939%20src/ADAL.NET/AuthenticationContext.cs%205%22%3A%20%7B%22html_url%22%3A%20%22https%3A//github.com/AzureAD/azure-activedirectory-library-for-dotnet/pull/140%23discussion_r22016192%22%2C%20%22comments%22%3A%20%5B%7B%22body%22%3A%20%22Why%20is%20this%20public%20now%3F%22%2C%20%22created_at%22%3A%20%222014-12-18T00%3A22%3A45Z%22%2C%20%22user%22%3A%20%7B%22avatar_url%22%3A%20%22https%3A//avatars.githubusercontent.com/u/466805%3Fv%3D3%22%2C%20%22html_url%22%3A%20%22https%3A//github.com/omercs%22%7D%7D%5D%2C%20%22title%22%3A%20%22File%3A%20src/ADAL.NET/AuthenticationContext.cs%3AL65-72%22%7D%7D%7D'></a>
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- [ ] <a href='#crh-comment-Pull edf2ed80b2caacb51e316d78126d122fc9c0a939 src/ADAL.NET/AuthenticationContext.cs 5'></a> <img src='http://www.codereviewhub.com/site/github-remaining.png' height=16 width=60>&nbsp;<b><a href='https://github.com/AzureAD/azure-activedirectory-library-for-dotnet/pull/140#discussion_r22016192'>File: src/ADAL.NET/AuthenticationContext.cs:L65-72</a></b>
- <a href='https://github.com/omercs'><img border=0 src='https://avatars.githubusercontent.com/u/466805?v=3' height=16 width=16'></a> Why is this public now?


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This was missing before. The Sync version of the API exists, so there is no reason to hide this one.