New build and pack scripts

I started working on the pack an build scripts in Powershell. It makes much more sense and keeping ruby as a build requirement does not make any sense.  

The other thing is the google code is pretty much dying. Clink has been migrated to github and conemu is using other distribution channels. Therefore I drafted `sources.json` - simple file that lists all the requirements for cmder. By using it, we will gain the power to **control the versions** of the software. I am hoping it can be turned into working updater one happy day.

I have never touched powershell language until today. So bare with me. 

### ToDo

##### Build script
- [x] Compilation of binary XP/Not XP
- [x] Flattening unnecessary subdirs for packages
- [x] Name and extension agnostic downloader
- [x] Information about current version
- [x] Error checking when downloading

##### Pack script
- [x] Rewrite the ruby