empty docObject passed to processTags

[nlundquist]

When processing documentation tags in comments of a JS source file bit-docs-js passes an empty docObject. This is done here:

bit-docs-js/process/code_and_comment.js

Lines 57 to 66 in 091899e

	processTags({
	comment: options.comment,
	scope: options.scope,
	docMap: options.docMap,
	docObject: {},
	tags: options.tags || {},
	siteConfig: options.siteConfig || {}
	}, function(newDoc, newScope){
	callback(newDoc, newScope);
	});

This causes usage of tags like @sourceref to fail, since it expects to be able to reference the src property of the docObject.

This issue is easily reproduced by trying to use @sourceref in any documentation comment of a JS file and then attempting to generate the docs. This will result in an error like the following:

TypeError: Cannot read property 'path' of undefined
    at Object.add (/Users/nlundqu/canjs/node_modules/bit-docs/lib/configure/node_modules/bit-docs-tag-sourceref/sourceref.js:18:21)
    at module.exports (/Users/nlundqu/canjs/node_modules/bit-docs/lib/configure/node_modules/bit-docs-process-tags/process-tags.js:95:29)
    at module.exports (/Users/nlundqu/canjs/node_modules/bit-docs/lib/configure/node_modules/bit-docs-js/process/code_and_comment.js:54:3)
    at /Users/nlundqu/canjs/node_modules/bit-docs/lib/configure/node_modules/bit-docs-js/process/javascript.js:26:13
    at Array.map (<anonymous>)
    at module.exports (/Users/nlundqu/canjs/node_modules/bit-docs/lib/configure/node_modules/bit-docs-js/process/javascript.js:25:29)
    at /Users/nlundqu/canjs/node_modules/bit-docs/lib/process/file.js:80:17
    at Array.some (<anonymous>)
    at processFile (/Users/nlundqu/canjs/node_modules/bit-docs/lib/process/file.js:79:40)
    at /Users/nlundqu/canjs/node_modules/bit-docs/lib/process/process.js:79:9

I attempted a naive fix by changing line 61 of code_and_comment.js above to docObject: options.docObject || {}, since options.docObject was defined while I was debugging, however this introduced new errors while processing the tags of other source files in the CanJS docs.