Add Github Flavored Markdown table export format (--gfm)

[enricobacis]

Export article data in Github Flavored Markdown table syntax.

./scholar.py --gfm -c 1 -a "Peter Norvig"

| Title          | A modern approach                                                                         |
| -------------- | ----------------------------------------------------------------------------------------- |
| Year           | 1995                                                                                      |
| Citations      | 23127                                                                                     |
| Versions       | 60                                                                                        |
| Cluster ID     | 16379301881339907933                                                                      |
| Citations list | http://scholar.google.com/scholar?cites=16379301881339907933&as_sdt=2005&sciodt=0,5&hl=en |
| Versions list  | http://scholar.google.com/scholar?cluster=16379301881339907933&hl=en&as_sdt=0,5           |

This text is also parsed in Github Flavored Markdown, so using the previous code here we get:

Title	A modern approach
Year	1995
Citations	23127
Versions	60
Cluster ID	16379301881339907933
Citations list	http://scholar.google.com/scholar?cites=16379301881339907933&as_sdt=2005&sciodt=0,5&hl=en
Versions list	http://scholar.google.com/scholar?cluster=16379301881339907933&hl=en&as_sdt=0,5

[enricobacis]

any news about this?