Update systemjs-builder to version 0.15.19 🚀

[greenkeeperio-bot]

Hello 👋

🚀🚀🚀

systemjs-builder just published its new version 0.15.19, which is not covered by your current version range.

If this pull request passes your tests you can publish your software with the latest version of systemjs-builder – otherwise use this branch to work on adaptions and fixes.

Happy fixing and merging 🌴

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The new version differs by 10 commits .

• 504917c 0.15.19
• b0a7616 allow plain canonicalizations of paths without trailing slash
• 4315a9e fix package name canonicalization
• eb475ed Merge pull request #612 from DevVersion/fix/ignore-sourcemaps
• c4094c3 fix(): loader should not fetch sourcemaps if disabled.
• f018a60 fix case for without source maps
• e6bd7c5 ensure Babel sourceFileName
• 3d95d8d sourceMappingURL detection fix
• 36b9c7c dev condition fix
• bbf0e11 buildStatic by default for production

See the full diff.

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