Fix up and add flexibility to HTCManager

[aminnj]

Currently, HTCManager is pretty rigid in terms of the job submission script and worker node script, and doesn't communicate properly as noted in #150 and #107.

To address the first, I added parameters that let one send extra inputs to the worker node, insert lines/ClassAds in the job submission script, add extra commands before julia is invoked on the worker node, and modify the location/command used in place of telnet. So one can do something like

myparams = Dict(
                :dir=>".",
                :exename=>"julia",
                :extrainputs=>["/path/to/file1.gz"],
                :extrajdl=>["RequestCpus = 1"],
                :extraenv=>["tar xf file1.gz", "setup_command()"],
               )
addprocs(HTCManager(8); myparams...)

and addprocs(HTCManager(8)) behaves as before.

To address the second, I made the master instance of julia bind to 0.0.0.0, as suggested in #107 (and explained in JuliaParallel/MPI.jl#222). I have the impression that most HTCondor worker processes are not on the submission/login node, so I guess the new binding address should be the default, though I defer to others on this.