Merge pull request #5 from mandeepsandhu/master

Minor changes to O2
Add acknowledgements.
Merge pull request #6 from mandeepsandhu/master

Qt5 support in O2
Merge pull request #7 from mandeepsandhu/master

Add Twitter XAuth support
Merge pull request #9 from mandeepsandhu/master

Add pluggable persistent storage support
Merge pull request #11 from mandeepsandhu/master

Update READM.md
Support for extra tokens in OAuth response
Added support for making extra tokens in OAuth response, available as a property

Certain OAuth service providers, provide extra information in
the form of additional tokens that are returned as aprt of a
successful OAuth exchange.

These additional tokens are made available as a read-only
property. The property's type is QMap<QString, QString>.
Support for extra tokens in OAuth response
Changed the extraTokens property to QVariantMap
Changed the extraTokens property in O1 & O2 to be a
QVariantMap to make it accessible in a QML context. The
existing QMap<QString, QString> was not accessible in QML.
Merge pull request #13 from mandeepsandhu/extra-token-parsing

Support for extra tokens in OAuth response