Encode all integer types

[otoolep]

This changes address two issues.

• When encoding integers, int and int32 are encoded as int64.
• When adding the path information for a shard to the diagnostics, a distinct array was added to the existing array. Instead the existing array should have had a new element appended to it.
• An integration test was added, which simply checks that when self-monitoring is enabled and occurs, that the database stays up. Also added explicit checks for negative values.

[jtakkala]

CLA for 443444c (#2366) signed.

[corylanou]

+1

[otoolep]

Thanks @corylanou