1) Moved basic utility code into base/ directory to make it clear which code
   doesn't depend on Flutter-specific knowldge.
2) Move the CommandRunner subclasses into a runner/ directory because these
   aren't commands themselves.

This test was a bad mock-based test that hasn't ever caught a bug but has
required a lot of maintenance. Currently its broken because its mock doesn't
match the real interface.

Now you can supply a route argument to flutter start:

  $ flutter start --route /foo

which will start the app at /foo instead of /.

Fixes #311

Now we suggest using -t to specify the main Dart file.

Fixes #53

We still have the --http option as a fallback for now. Once we're confident the
--no-http version works, we'll drop the --http support.

Also, create the FLX in a temp directory and then delete the temp directory
when we're done. Finally, pull the Linux artifacts from the cloud storage
bucket that the buildbot is uploading to.

wrap up first daemon implementation

This flag builds a local FLX file and pushes that to the device instead of
using an HTTP server.

Increase the test timeout for the `init` test to 2 minutes (test was timing out downloading assets on appveyor).

remove a runInShell arg on windows when launching pub

Instead of calling through `pub` to invoke build, this patch refactors the
build command so that it can be called directly.

This patch improves the error handling for several arbitrary issues I
encountered while experimenting with the tool this evening.

This patch makes `flutter start` work without a clone of the engine git
repository. Making this work pulled a relatively large refactor of how the
commands interact with application packages and devices. Now commands that want
to interact with application packages or devices inherit from a common base
class that holds stores of those objects as members.

In production, the commands download and connect to devices based on the build
configuration stored on the FlutterCommandRunner. In testing, these fields are
used to mock out the real application package and devices.

Also fixes some minor bugs with iOS and Android interactions.

I'm trying to get a feel for the code by writing some simple cleanup patches.

Also update tests to be compatible with the presence of iOS and add tests for list and install.

Add listen command and basic test, and don’t do unnecessary repeated work when listening or poking the android server.