added definitions for joi
issue #2033 - subtract method added to Duration type
Merge pull request #2065 from Diullei/master

issue #2033 - "subtract()" method added to Duration type
fix minimatch/minimatch.d.ts
fix header of space-pen/space-pen.d.ts
Merge pull request #2064 from Bartvds/def/joi

created definitions for joi
Merge pull request #2066 from vvakame/fix-minimatch

fix minimatch/minimatch.d.ts
Merge pull request #2067 from vvakame/add-header-to-space-pen

fix header of space-pen/space-pen.d.ts
Merge pull request #2068 from borisyankov/docs/contribute

linked CONTRIBUTING.md to org site page
moved contributors from README.md to CONTRIBUTORS.md