Fix handling of non-Int row indices (JuliaData#1177)

Non-Int row-indices were not being correctly converted to Int.

- explicit conversion to Vector{Int}
- test-cases added

Fix more 0.6 depwarns (JuliaData#1171)

Use registered Documenter.jl instead of cloning directly from repository

Query docs backport (JuliaData#1126)

* Add documentation for Query.jl

DataFrames v0.8.5 [49da3cc]

DataFrames v0.8.4 [30aae2a]

DataFrames v0.8.3 [ef36bd3]

DataFrames v0.8.2 [d1fc340]

DataFrames v0.8.0 [2fcc122]