Don't put array items on the same line when persisting

Rockspec fields with array values (e.g. dependencies) are
typically written with each item on its own line. This change
makes `luarocks new-version` follow this style, too.

src/luarocks/persist.lua

@@ -124,13 +124,10 @@ write_table = function(out, tbl, level, field_order)
    out:write("{")
    local sep = "\n"
    local indentation = "   "
-   local indent = true
    local i = 1
    for k, v, sub_order in util.sortedpairs(tbl, field_order) do
       out:write(sep)
-      if indent then
-         for n = 1,level do out:write(indentation) end
-      end
+      out:write(indentation:rep(level))
 
       if k == i then
          i = i + 1
@@ -147,17 +144,11 @@ write_table = function(out, tbl, level, field_order)
       end
 
       write_value(out, v, level, sub_order)
-      if type(k) == "number" then
-         sep = ", "
-         indent = false
-      else
-         sep = ",\n"
-         indent = true
-      end
+      sep = ",\n"
    end
    if sep ~= "\n" then
       out:write("\n")
-      for n = 1,level-1 do out:write(indentation) end
+      out:write(indentation:rep(level - 1))
    end
    out:write("}")
 end