Add bower update --save functionality

[contolini]

This PR lets bower update update bower.json via a --save flag. It mimics npm's update behavior.

Current behavior:

• bower update updates components in bower_components/ while respecting components' semver in bower.json. For example, if bootstrap is listed as ~2.2.0 in bower.json, running bower update will update bower_components/bootstrap to 2.2.2 because 2.2.2 is the latest version greater than 2.2.0 but less than 3.0.0.
• bower.json is not modified.
• Here are steps to test this behavior locally.

New behavior proposed by this PR:

• bower update --save does the same stuff above but it also edits bower.json. In the above example, bootstrap would now be listed in bower.json as ~2.2.2.
• bower update --save-dev works the same but for dev dependencies.
• Extraneous dependencies (components that exist in bower_components/ but aren't listed in bower.json) are ignored.

See #2035 and #1468.

@bower/contributors please review. Feedback is appreciated.

[sheerun]

Looks promising :) Could you squash the commits and force-push them?

[contolini]

@sheerun Definitely. Is AppVeyor failing because of this PR? Or is it just having a bad day?

[sheerun]

Yes, appveyor is failing because of timeout on one test. Maybe you need to use nock to mock some connection or something (optionally increase maximum timeout for this test).

Don't look at node 0.10 on appveyor because it's failing for unrelated issues..

[contolini]

Cool, for now I just increased the timeout for that test file. I'll look into properly mocking the http requests when I get some more time. There are other update issues I'd like to tackle (esp. #256) that involve the same files.

[sheerun]

Should I wait until you add tests for updating a single package?

[colinodell]

+1

[contolini]

@sheerun No, unfortunately that bug (#256) is a complicated one. If y'all are okay with the code in this PR, I think it's ready to be merged.

[sheerun]

Thank you

[jonathansolorzn]

I've just runned npm install bower - & bower update --save and the depencies are updated, but bower.json isn't updated, I mean the depency version doesn't change

[sheerun]

It will be released as bower 1.6.9

[jonathansolorzn]

Oh, ok