Implemented version lists.

Further work on this is still needed. Currently there is no sorting or filtering of any kind. In addition,
changes need to be made to fix issues with bad ETags since the current system here is based on MultiMC 4's
version list system before it was fixed.
Merge branch 'master' of git://github.com/peterix/MultiMC5

Conflicts:
	CMakeLists.txt
	gui/mainwindow.cpp
Fix quazip issues.
Merge branch 'master' of git://github.com/peterix/MultiMC5
Make the new instance dialog support instance types.
Implement instance creation.
Removed old plugin system and implemented some version list stuff.
Implemented version list sorting.

Resolves MMC-8:
	https://jira.forkk.net/browse/MMC-8
Allow users to filter out MCNostalgia and Snapshots from the version list.

Resolves JIRA issue MMC-9:
	https://jira.forkk.net/browse/MMC-9
Removed files I forgot to remove earlier (oops)
Made the version list load in the background on startup.

Resolves JIRA issue MMC-11:
	https://jira.forkk.net/browse/MMC-11
The default selected version is now the current stable version.

Resolves JIRA issue MMC-10:
	https://jira.forkk.net/browse/MMC-10
Implemented version selection stuff.
Implement basic game updater.

Resolves MMC-4: https://jira.forkk.net/browse/MMC-4
Fixed timestamp parsing in version lists.
Implemented LWJGL version lists.

The LWJGL list actually doesn't use tasks for loading. Instead, it takes advantage of the
QNetworkAccessManager's asynchronous requests. This is a system that I may look to implement for other version
lists and things such as the Minecraft version list and possibly even instance mod lists.

Loading things this way means that code that wants to load a list can simply call the load list function, rather
than having to get a task from the list and execute the task. Unfortunately, it also means we can't have task
progress dialogs for loading lists, but it shouldn't really be too difficult to write one that works with this
system.

At some point in the future, I'll probably end up putting all the code for this method of loading lists into a
base class and then update the other lists to support it.
Use shared pointers to fix incompatibility with new Qt