alarm/devtools-alarm: Add `devtools` to `conflicts` and `provides`.

This
  - Prevents file conflict errors if `devtools` is installed while
    `devtools-alarm` is installed and vice versa.
  - Allows `devtools-alarm` to act as a substitute for `devtools` in the
    dependency lists of other packages.
Merge pull request #720 from paraxor/master

alarm/devtools-alarm: Add 'devtools' to 'conflicts' and 'provides'.