Don't let elpa download dependencies

Since el-get also downloads dependencies we end up installing things
twice.

* methods/el-get-elpa.el (el-get-elpa-install): call
  package-download-transaction instead of package-install.
Don't let elpa activate el-get installed packages

* el-get.el (el-get-do-init): add non-elpa package to
  package-activated-list so elpa thinks knows they are already
  activated.