Update 07-flxsave.html.md

Added flush() on sample code, necessary to actually save the data. Added import header.
Update 07-flxsave.html.md

- Fixed 2 broken links (to the demo and a docs page)
- Added flush() description
- Changed link of API to Haxe version instead of AS3
Merge pull request #21 from AndreiRegiani/patch-4

Update 07-flxsave.html.md