Release 15.10.0

• Upgrade eslint-config-standard 12.0.0 -> 13.0.0 (43d9432)
• Update rules for standard.js 13 (c769d21)
• Upgrade gulp-shared-tasks 0.30.20 -> 0.30.21 (07ee5e9)
• Upgrade gulp-shared-tasks 0.30.17 -> 0.30.20 (cae9b06)
• Upgrade ava 2.1.0 -> 2.2.0 (b25c702)
• Upgrade gulp-shared-tasks 0.30.16 -> 0.30.17 (3c18a03)
• Upgrade gulp-shared-tasks 0.30.15 -> 0.30.16 (d838acf)
• Upgrade gulp-shared-tasks 0.30.14 -> 0.30.15 (d48a6ee)
• Upgrade execa 2.0.2 -> 2.0.3 (8a1619b)
• Upgrade gulp-shared-tasks 0.30.13 -> 0.30.14 (ee2e363)
• Upgrade gulp-shared-tasks 0.30.12 -> 0.30.13 (460275e)
• Upgrade husky 2.7.0 -> 3.0.0 (bc1324e)
• Update Travis NPM_TOKEN (c437c6d)
• Upgrade execa 2.0.1 -> 2.0.2 (56265f8)
• Upgrade gulp-shared-tasks 0.30.11 -> 0.30.12 (25e1143)
• Upgrade husky 2.6.0 -> 2.7.0 (4061229)
• Upgrade gulp-shared-tasks 0.30.10 -> 0.30.11 (9c7ec3e)
• Upgrade husky 2.5.0 -> 2.6.0 (37dd684)
• Upgrade execa 2.0.0 -> 2.0.1 (bf9040e)
• Upgrade gulp-shared-tasks 0.30.9 -> 0.30.10 (1b93ee4)