Set Julia 1.3 as minimum supported version

[jpsamaroo]

Once a new LTS is officially announced, 1.3 will also be dropped in favor of that release (probably 1.6).

[krynju]

Ok I looked around at compats for the Tables and testing dependencies

Arrow 1.0 - tables interface was added in 0.3, but shortly after 1.0 was released, so 1.0 seems like a good target
CSV 0.8 - it dropped the DataFrames dependency at that release
DataFrames 1.0 - some Tables.jl interface changes were applied on 1.0, seems like a good target
Tables 1.1 - partition interface was added (used in dtable)
TableOperations 1.0 - makepartitions was added (used in dtable)

[compat]
Arrow = "1.0"
CSV = "0.8"
Colors = "0.10, 0.11, 0.12"
DataFrames = "1.0"
MemPool = "0.3.4"
Requires = "1"
StatsBase = "0.28, 0.29, 0.30, 0.31, 0.32, 0.33"
TableOperations = "1"
Tables = "1.1"
julia = "1.0"

[jpsamaroo]

None of the CI failures seem to be due to this change.