Merge pull request #66 from khawkins/unstable

Mobile SDK: Merging unstable to git.soma
Merge pull request #67 from SalesforceMobileSDK/unstable

Mobile SDK: Merging unstable into community
Added more methods on SFPreferences, scoped some user defaults
Merge branch 'community' of git.soma.salesforce.com:SalesforceMobileSDK/SalesforceMobileSDK-iOS into community
Allow singleton method to return nil when there is no current user
Added new mechanism to notify consumer of any changes at the user account level
Ensure valid user
Merge pull request #68 from jbovet/community

Added more methods on SFPreferences, scoped some user defaults
Merge pull request #69 from khawkins/unstable

Mobile SDK: Merging unstable to git.soma
Merge pull request #70 from SalesforceMobileSDK/unstable

Mobile SDK: Merging unstable into community
Fixed an issue accessing the array on multiple threads
Merge pull request #71 from jbovet/community

Fixed an issue accessing the array on multiple threads
First round of user switching functionality
Fleshing out more user management actions
Login account, logout specific account, delete account updates
Adding current user info target
Couple of code cleanup requests
Merge pull request #73 from khawkins/unstable

Mobile SDK: Merging unstable to git.soma
Merge remote-tracking branch 'gitsoma/unstable' into gs_community
Merge pull request #75 from khawkins/gs_community

Mobile SDK: Merging unstable into community