Merge pull request #43 from nerds-odd-e/comment_support

Support for parsing Comments
version bump 0.3.7: comments and coverage

- parsing comments (h/t @kinwahlai, @hmalphettes)
- XLSX.version now exposed in source
- code coverage
- updated SSF to 0.5.2
- updated tests/files
version bump 0.3.8: more formatting

- updated SSF to 0.5.3

tests without baselines now try to generate CSV output
version bump 0.3.9: general format used by default

(when no format or style is found, use general)

Other whitespace cleanup
version bump 0.3.10: xlsm support

different workbook content type, same representation
README updates [ci skip]
version bump 0.4.0: very basic XLSB support

subfiles reshuffled (XLSB and XLSX/XLSM content separated)
version bump 0.4.1: more XLSB + cleanup

- updated ssf to 0.5.4
- cleaned up CSV string output
- added CSV tests (from test_files)
- passes lint
- inlineStr actually parses <is> block
- more XLSB bits
version bump 0.4.2: using jszip module on node

- updated test_files
- new dependency in node: jszip
travis ignore node 0.8 due to jszip bug

See https://github.com/Stuk/jszip/issues/84 for more info
version bump 0.4.3: shared strings and formatting

- XLSB basic support for number formats
- removed extraneous Strings table element
- formatting xml tags (rich_stress_test)
- updating test_files to 20130130
version bump 0.5.0: changes to cell interface

Cell object stores the formatted text in the `.w` field
- Raw format and types are preserved in the `.t`, `.v` fields
- Accessors have been updated to use the field

updates for older OOXML:
- ECMA-376 makes reference to old sstItem shared string item
- [MS-XLSX] xmlns for workbook
xlsb browser fix
version bump 0.5.1: field reorg

- cell.r holds the raw rich text, cell.h now holds the html
  (version 0.5.0 cell.raw -> cell.r, cell.r -> cell.h)
- similar changes to comments and XLSB generation
- removed some unused binary methods
version bump 0.5.2: chores

- node jszip updated to 2.1.0 as per https://github.com/Stuk/jszip/issues/84
- travis 0.8 tests restored
- get_formulae ignores undefined values
- updated test_files to 20140206
version bump 0.5.3: options!

- read and readFile accept opts argument:
o cellNF (default false) true -> cell.z holds number format string
o sheetStubs (default true) false -> stub cells not emitted

- name consistency (parse_workbook -> parse_wb_xml)
- README updates
- CONTRIBUTING notes added
version bump 0.5.4: more options

- cellHTML controls HTML generation
- cellFormula controls formula output
- sheetStubs now defaults to false

- cleaned up unnecessary CSV quotes (fixed #45)
- updated test_files to 20140211
- updated SSF to 0.5.7
- removed unused main function
- removed some dead code
version bump 0.5.5: sheet names optimization

- bookSheets option skips worksheet parsing (used by xlsx2csv)
- filtered tests (by file extension)
- XLSB formulae stubs
test cleanup
Parse custom properties and and return them as a hash workbook.Custprops