chore: explicit update of istanbul dependnecies (#562)

package.json

@@ -83,12 +83,12 @@
     "find-up": "^1.1.2",
     "foreground-child": "^1.5.3",
     "glob": "^7.0.6",
-    "istanbul-lib-coverage": "^1.0.2",
-    "istanbul-lib-hook": "^1.0.5",
-    "istanbul-lib-instrument": "^1.7.0",
-    "istanbul-lib-report": "^1.0.0",
-    "istanbul-lib-source-maps": "^1.1.1",
-    "istanbul-reports": "^1.0.2",
+    "istanbul-lib-coverage": "^1.1.0",
+    "istanbul-lib-hook": "^1.0.6",
+    "istanbul-lib-instrument": "^1.7.1",
+    "istanbul-lib-report": "^1.1.0",
+    "istanbul-lib-source-maps": "^1.2.0",
+    "istanbul-reports": "^1.1.0",
     "md5-hex": "^1.2.0",
     "merge-source-map": "^1.0.2",
     "micromatch": "^2.3.11",
@@ -97,9 +97,9 @@
     "rimraf": "^2.5.4",
     "signal-exit": "^3.0.1",
     "spawn-wrap": "1.2.4",
-    "test-exclude": "^4.0.0",
-    "yargs": "^7.0.2",
-    "yargs-parser": "^4.0.2"
+    "test-exclude": "^4.1.0",
+    "yargs": "^7.1.0",
+    "yargs-parser": "^5.0.0"
   },
   "devDependencies": {
     "any-path": "^1.3.0",