Changed `git` and `dev` to not check dependencies when installing.

They are still checked in `path`.

Rationale:

 * Many git repos or development directories do not have a valid haxelib.json file
 * Even if they do have a valid haxelib.json file, the dependencies may point to a development version of the dependency - not one that is available on lib.haxe.org.
 * Dependencies are still evaluated at during "haxelib path", so using "-lib mydevlibrary" will still evaluate dependencies correctly.
 * If a dependant library is not available, trying to compile will give "Library mylib is not installed : run haxelib install mylib".  This is pretty acceptable IMO.

Also:

 * More unit tests for Data.hx
 * Better error handline in Data.hx

Affected Issues:

Fixes #40
Fixes #48
Fixes #50 (I couldn't reproduce, but this should fix anyway)
Fixes #51 (Needs testing)

and the tests help make progress on Issue #38
Fix URL confusion.
Give more info after "haxelib git", so it's easier to know that it worked
Give more useful error if "haxelib install" doesn't have permission.

Fixes Issue #43
Cleaned up the tests a little bit
Check tags are valid too
Small fix for tags type checking
Added support for "classPath" in haxelib.json
Accidentally committed a trace... whoops
Ignore corrupt repos in `haxelib list`
Handle `haxelib update` on a dirty git repo

If there are uncommitted changes, show a diff and offer to do a reset
so that the pull will work.
Get rid of wrong extra argument
Update script to use 3.0 folder for files
Suppress "no such version" error when installing from non lib.haxe.org location

If you install from a zip file or a different repo, it tries to post stats to lib.haxe.org.
If the project or version you installed doesn't exist there, it throws an error.

This shouldn't be a show stopper
Slightly clearer feedback during selfupdate
Update JSON, bump version number, include ConvertXml.hx in packed library
Add schema.json from Zachary Dremann's gist

https://gist.github.com/Dr-Emann/5673379

My alterations:

 * Removed description as required (it's not)
 * Removed min lengths of 2, when they are 0
 * Changed minimum name length to 2 (does this apply to users also?)
 * Set additionalProperties to true (so people could extend it for their own needs)

Feel free to argue.  I still haven't added classPath yet.
Add classPath to schema
Cleaned up submission process.

It now lets you pick which user you are submitting as, and retry your
password if you get it wrong
Don't print "checkout NULL" when using git without specifying branch