Foundationdb

Added support for testing [FoundationDB](http://www.foundationdb.com) with Jepsen. 

Includes Salticid support for:
* Installing FoundationDB and configuring for triple replication
* Completely removing FoundationDB (nuking), including data and log files
* Collecting the log files
* Removing the log files

Includes three tests for Jepsen:
* foundationdb: Create a new key/value pair for a list of elements, retries failed transactions using the FoundationDB API's automatic [transaction retry loop](https://foundationdb.com/documentation/developer-guide.html#transaction-retry-loops)
* foundationdb-append: Append a list of element to a single key/value pair, retries failed transactions using the FoundationDB API's automatic transaction retry loop
* foundationdb-append-noretry: Append a list of element to a single key/value pair, does not retry failed transactions

To run these tests yourself, you'll need to:
* Install the [FoundationDB client](https://foundationdb.com/get) on the machine running Jepsen (you don't need the server)
* Copy /etc/foundationdb/fdb.cluster from one of the database servers to the machine running Jepsen. You can put in either the [default cluster location](https://foundationdb.com/documentation/administration.html#default-cluster-file), or in the directory from which you'll run Jepsen