Merge pull request kulshekhar#410 from lijunle/ts-once

Avoid transpile the TypeScript code twice.

closes kulshekhar#406, closes kulshekhar#407

Merge pull request kulshekhar#351 from kulshekhar/cleanup

Cleanup

Merge pull request kulshekhar#373 from martijnthe/change-entry-to-pre…

…processor.js

Enable using 'ts-jest' package name as transform (Take 2) + fix kulshekhar#367

Merge pull request kulshekhar#370 from GoodForOneFare/fix-commonjs-tr…

…ansform-assignment

Don't accumulate commonjs module transforms

Merge pull request kulshekhar#368 from kulshekhar/revert-363-change-e…

…ntry-to-preprocessor.js

Revert "Change the package entry point to preprocessor.js itself"

Merge pull request kulshekhar#363 from martijnthe/change-entry-to-pre…

…processor.js

Change the package entry point to preprocessor.js itself

Merge pull request kulshekhar#354 from richsilv/fix-missing-plugins

Fix postprocess bug when babel config is supplied with no plugins

Merge pull request kulshekhar#348 from Bnaya/start-dir-cwd

Set the start dir of looking for tsconfig to process.cwd()

Merge pull request kulshekhar#344 from misantronic/master

fix: add startDir to if-clause

Closes kulshekhar#343

Merge pull request kulshekhar#342 from kulshekhar/fix-238

Find tsconfig.json by traversing up