Recommend `yargs` over `optimist`

Substack has deprecated the `optimist` package, recommending the use of
it's successor, `yargs`.
Merge pull request #323 from gulpjs/recommend-yargs

Recommend `yargs` over `optimist`
add missing spaces into function declarations
remove spaces before '(' to follow style guide
+ update readme - plugin example
Merge pull request #327 from stevermeister/man-update

+ update readme - plugin example
Merge pull request #326 from t3chnoboy/master

add missing spaces into function declarations
Add completion dir to package.json files
Merge pull request #342 from thejameskyle/patch-1

Include completion files for npm
fix completion not being included
closes #345
Actualize mocha recipe

Closes #233
Merge pull request #346 from floatdrop/master

Actualize mocha recipe
Another strategy for incremental builds

While the `gulp-changed` and `gulp-cached` plugins work great with 1:1 src:dest file mapping, they should not be used for n:1 src:dest mapping.  With plugins like `gulp-concat`, `css-sprite`, etc. that generate a single output file given many input files, you want to compare the modification time of the output file to the modification file of each input file (and use all if any are newer).

The `gulp-newer` plugin works with both 1:1 and n:1 src:dest mapping by comparing `mtime`.
Merge pull request #351 from tschaub/patch-1

Another strategy for incremental builds
closes #366
Rename concat to merge.

https://github.com/dominictarr/event-stream#merge-stream1streamn
Merge pull request #367 from steida/master

Rename concat to merge.
Update using-coffee-script-for-gulpfile.md
Merge pull request #373 from meleyal/patch-1

Update "Using coffee-script for gulpfile" recipe with link to cult