add encrypted data bag support

Adds support for storing sumologic authentication credentials in an
encrypted databag instead of storing them in clear text attributes.
Update the readme with EncDatabag options

Add a description of the new attributes for working with
encrypted data bags to the readme.
bump the version number
wrap properties fields with "'s

The current sumo.conf properties file isn't able handle some symbols.
For example, a 31 character password containing this string
"(2/42\t^Vk->?w=h!%Mi" is unreadable by the current parser. While
adding double quotes around the password didn't help in this case, it
may reduce the number of this symbol failures (and at the very least,
has no negative impact).
Merge pull request #7 from lithiumtech/master

Encrypted data bag support for credentials