Fix profile

[ghost]

1. Upgraded MongoDb CSharp Driver to v1.5
2. Fixed profile provider to handle non-persisted profiles
3. Improved connection string usage:

• Now it's possible to specify connection string name in "connectionString" property:

<add name="MongoDBRoleProvider" type="MongoDB.Web.Providers.MongoDBRoleProvider" applicationName="/" connectionString="DefaultMongoConnection" />

• It's not necessary to specify database name in config - it can be part of connection string, say:

<add name="Something" connectionString="mongodb://127.0.0.1/Database?safe=true" />