add test deps

[KristofferC]

Tests still fails with:

ERROR: LoadError: EOFError: read end of file
Stacktrace:
 [1] read at ./iobuffer.jl:212 [inlined]
 [2] read at ./stream.jl:856 [inlined]
 [3] deserialize at /Users/kristoffer/julia/usr/share/julia/stdlib/v1.2/Serialization/src/Serialization.jl:722 [inlined]
 [4] deserialize(::Base.PipeEndpoint) at /Users/kristoffer/julia/usr/share/julia/stdlib/v1.2/Serialization/src/Serialization.jl:709
 [5] top-level scope at /Users/kristoffer/.julia/packages/SymbolServer/f6geS/src/clientprocess/clientprocess_main.jl:16
 [6] include at ./boot.jl:328 [inlined]
 [7] include_relative(::Module, ::String) at ./loading.jl:1094
 [8] include(::Module, ::String) at ./Base.jl:31
 [9] exec_options(::Base.JLOptions) at ./client.jl:295
 [10] _start() at ./client.jl:464
in expression starting at /Users/kristoffer/.julia/packages/SymbolServer/f6geS/src/clientprocess/clientprocess_main.jl:15

on 1.2-rc1 and 1.1.

[davidanthoff]

#24