Change from ensure_loaded/1 to ensure_compiled/1

[TeoDiaz]

Fixes #358

We can't use ensure_compiled!/1 for versions under 1.12+

[josevalim]

@TeoDiaz we should rename the function to ensure_compiled! and we should also change it to ensure_compiled! on the if branch.

[josevalim]

I pushed one commit but I left the renaming to you. :)

[coveralls]

Pull Request Test Coverage Report for Build 49bf1da0219bcb3ae32d5b2e3ac398d02fc8653d-PR-359

• 3 of 3 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 90.738%

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Totals
Change from base Build da71fb6d2c9e0a607376b5bb945c80ffc9e18b9b:	0.0%
Covered Lines:	529
Relevant Lines:	583

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💛 - Coveralls

[TeoDiaz]

I pushed one commit but I left the renaming to you. :)

Done! Thanks 😉

[whatyouhide]

Thanks @TeoDiaz! 💟