Merge pull request #1 from special/master

Only attempt to use authentication methods which we have credentials for
[mcp-account-manager-uoa] Fix assertation when signon data is missing from an identity
[mcp-account-manager-uoa] Remove create/delete account functions

We don't want externally created telepathy accounts stored with
libaccounts.
Revert "[mcp-account-manager-uoa] Remove create/delete account functions"

This reverts commit 16f34db1fe3d1dcc57f6ad3d00810fb8b63a9ae3.
[mcp-account-manager-uoa] Disable account creation and deletion functions