Prevent tasks from running if electric.config.js file is not found

[zenorocha]

Nowadays, if you type electric run on a folder that doesn't contain the electric.config.js file you get an error.

➜  wedeploy.com (master) ✔ electric run

Running 'run'...
[13:17:34] Starting 'build'...
[13:17:34] Starting 'clean'...
[13:17:34] Starting 'clean:dest'...
[13:17:34] Starting 'clean:temp'...
[13:17:34] Finished 'clean:dest' after 6.62 ms
[13:17:34] Finished 'clean:temp' after 3.14 ms
[13:17:34] Finished 'clean' after 8.24 ms
[13:17:34] Starting 'front-matter'...
[13:17:34] Starting 'static'...
[13:17:34] Starting 'styles'...
[13:17:34] Starting 'vendor'...
[13:17:34] Starting 'vendor:codemirror'...
[13:17:34] Starting 'vendor:custom'...
[13:17:34] Starting 'vendor:senna'...
[13:17:34] Finished 'vendor:custom' after 5.71 ms

stream.js:74
      throw er; // Unhandled stream error in pipe.
      ^
Error: Error: ENOENT: no such file or directory, open '/Users/zeno/Projects/wedeploy.com/src/site.json'

We could do something like gulp and display something message to the user:

➜  wedeploy.com (master) ✗ gulp
[13:18:47] Local gulp not found in ~/Projects/wedeploy.com
[13:18:47] Try running: npm install gulp