Move i-bem__i18n.bemhtml related tests to i-bem__i18n.test.bemhtml/
Test added for BEM.I18N nested call within bemjson
i-bem__i18n core's test runner renamed to *-test.js

Code-style of test runners fixed
npm test command adopted to recent changes
Use "exports.apply" hack to fix #217
i-bem__i18n.bemhtml: Use non-strict comparing \w null to check "ctx.content"
Merge pull request #219 from bem/bem/217@v1

i-bem__i18n's "content" property fixed