fix several exceptions when validating files missing jsdoc tags

```
TypeError: Cannot call method 'iterateByType' of null
    at Object.validateCheckParamNames (/Volumes/samara/projects/boneskull/angular-tags/node_modules/jscs-jsdoc/lib/rules/validate-jsdoc/check-param-names.js:13:16)
    at /Volumes/samara/projects/boneskull/angular-tags/node_modules/jscs-jsdoc/lib/rules/validate-jsdoc.js:96:27
    at Array.forEach (native)
    at /Volumes/samara/projects/boneskull/angular-tags/node_modules/jscs-jsdoc/lib/rules/validate-jsdoc.js:95:32
    at Array.forEach (native)
    at Object.JsFile.iterateNodesByType (/Volumes/samara/projects/boneskull/angular-tags/node_modules/grunt-jscs/node_modules/jscs/lib/js-file.js:284:42)
    at /Volumes/samara/projects/boneskull/angular-tags/node_modules/jscs-jsdoc/lib/rules/validate-jsdoc.js:86:18
    at Array.forEach (native)
    at Object.module.exports.check (/Volumes/samara/projects/boneskull/angular-tags/node_modules/jscs-jsdoc/lib/rules/validate-jsdoc.js:78:29)
    at null.<anonymous> (/Volumes/samara/projects/boneskull/angular-tags/node_modules/grunt-jscs/node_modules/jscs/lib/string-checker.js:285:26)

```

```
TypeError: Cannot call method 'iterateByType' of null
    at Object.validateCheckParamNames (/Volumes/samara/projects/boneskull/angular-tags/node_modules/jscs-jsdoc/lib/rules/validate-jsdoc/check-redundant-params.js:13:16)
    at /Volumes/samara/projects/boneskull/angular-tags/node_modules/jscs-jsdoc/lib/rules/validate-jsdoc.js:96:27
    at Array.forEach (native)
    at /Volumes/samara/projects/boneskull/angular-tags/node_modules/jscs-jsdoc/lib/rules/validate-jsdoc.js:95:32
    at Array.forEach (native)
    at Object.JsFile.iterateNodesByType (/Volumes/samara/projects/boneskull/angular-tags/node_modules/grunt-jscs/node_modules/jscs/lib/js-file.js:284:42)
    at /Volumes/samara/projects/boneskull/angular-tags/node_modules/jscs-jsdoc/lib/rules/validate-jsdoc.js:86:18
    at Array.forEach (native)
    at Object.module.exports.check (/Volumes/samara/projects/boneskull/angular-tags/node_modules/jscs-jsdoc/lib/rules/validate-jsdoc.js:78:29)
    at null.<anonymous> (/Volumes/samara/projects/boneskull/angular-tags/node_modules/grunt-jscs/node_modules/jscs/lib/string-checker.js:285:26)

```

```
TypeError: Cannot read property 'value' of undefined
    at DocComment.<anonymous> (/Volumes/samara/projects/boneskull/angular-tags/node_modules/jscs-jsdoc/lib/rules/validate-jsdoc/check-redundant-params.js:22:29)
    at DocComment.<anonymous> (/Volumes/samara/projects/boneskull/angular-tags/node_modules/jscs-jsdoc/lib/jsdoc.js:74:16)
    at Array.forEach (native)
    at DocComment.iterateByTypes [as iterateByType] (/Volumes/samara/projects/boneskull/angular-tags/node_modules/jscs-jsdoc/lib/jsdoc.js:70:19)
    at Object.validateCheckParamNames (/Volumes/samara/projects/boneskull/angular-tags/node_modules/jscs-jsdoc/lib/rules/validate-jsdoc/check-redundant-params.js:14:20)
    at /Volumes/samara/projects/boneskull/angular-tags/node_modules/jscs-jsdoc/lib/rules/validate-jsdoc.js:96:27
    at Array.forEach (native)
    at /Volumes/samara/projects/boneskull/angular-tags/node_modules/jscs-jsdoc/lib/rules/validate-jsdoc.js:95:32
    at Array.forEach (native)
    at Object.JsFile.iterateNodesByType (/Volumes/samara/projects/boneskull/angular-tags/node_modules/grunt-jscs/node_modules/jscs/lib/js-file.js:284:42)

```