Check if rmg/rmgmolecule are in env rather than try-catch

Author: mjohnson541

deps/build.jl

@@ -13,9 +13,7 @@ if PyCall.pyversion.major != 3 || PyCall.pyversion.minor != 7
     end
     Conda.add("nomkl")
     Conda.add("numpy")
-    try 
-        pyimport("rmgpy")
-    catch e
+    if (not Conda.exists("rmg")) && (not Conda.exists("rmgmolecule"))
         Conda.add_channel("hwpang")
         Conda.add("rmgmolecule")
     end