Make comments jsdoc compatible

[henridf]

Similar to what was done in #18 for lib/DataFrame.js in 9675dd3, but for the other API wrappers in lib/

• DataFrame.js
• DataFrameReader.js
• GroupedData.js
• functions.js
• sqlContext.js
• Column.js

Row.js doesn't need to be documented (at least yet) -- it is only used internally so far.

[henridf]

Note that (as of 1497125) jsdoc creates docs for the class SQLContext and its constructor, which isn't accessible outside of sqlContext.js. Need to figure out how to address this.

[henridf]

Also need to make a pass to do something about the backticks in comments as they currently just add noise. One option is to remove them, another is to replace them by , and another is to leave them and look into using the markdown plugin.

[henridf]

lib/sqlContext.js done in 1497125 and 81be036

lib/DataFrameReader.js done in c73dbdc

lib/GroupedData.js done in bdf9d1d

[henridf]

lib/functions.js done in b30df94

[henridf]

lib/Column.js docs done in da6c0cd and db2f67e