Change watch extension from 'elm' to '.elm'

[fourcube]

For me, this fixed the problem of automatic hot-swap not working on Linux (Ubuntu 15.04).

Unfortunately, this does not fix hot-swap on MacOS (10.11). I was able to verify that this triggers sendHotSwap, but no data arrives through the WebSocket inside the browser.

See the 'hot-reload not working' part of #168.

[pgaertig]

@fourcube thanks for this PR! You have just saved a few linuxers from ditching Elm. This may help anyone struggling with the same issue on Linux:

1. Prepare to build Elm from sources.

2. Change makeRepo in BuildFromSource.hs this way:

   makeRepo root projectName version =
    do  -- get the right version of the repo
      if projectName == "elm-reactor"
        then git [ "clone", "https://github.com/fourcube/" ++ projectName ++ ".git" ]
        else git [ "clone", "https://github.com/elm-lang/" ++ projectName ++ ".git" ]
      setCurrentDirectory projectName
      git [ "checkout", version, "--quiet" ]

3. runhaskell BuildFromSource master
4. Freshly fixed elm-reactor is ready at /Elm-Platform/master/elm-reactor/dist/dist-sandbox-8e8030c8/build/elm-reactor/elm-reactor.

@evancz @fourcube 's PR is very trivial but practically fixes elm-reactor for Linux users. What it the problem to merge it into master, or even releasing 0.16.1?

[rassie]

@pgaertig In my limited testing (YMMV), hot-swapping works with this patch, but something else is broken -- e.g. the clock example stops working, i.e. the hands stop moving after hot-swapping.

[rassie]

Have to correct myself: seems this PR is obsolete since ab0d2cde35b9e2fcb54e24c47c55d6a6c55b244a where the missing dot has been added. Will have to test whether elm-reactor is now working in master.

@fourcube Care to close this PR to reduce confusion?

[fourcube]

@rassie sure, closing it right now.