Libification.

Jekxyl is now a vendor/top-namespace, where libraries are located in
Library/Jekxyl/. We have two libraries for now: Jekxyl\Builder and
Jekxyl\Post. Binaries are located in Bin/ and the application is located
in Application/ containing the In/ and Out/ directories.
Merge pull request #1 from Hywan/libification

Libification.
Add very basic layout per post feature.
Update gitignore for new structure.
Extract posts meta parsing.
Fix a bug with index rendering.
Remove metas used to generate site from output (Close #2).
Extract page title used in index from a meta.
Use title meta to set HTML page title.
Fix spacing (thanks @Hywan).
Use Hoa\File finder to find posts.