Truncate post slugs when importing from Tumblr.

Fixes #481.
pygments options for pygments.rb
Added a configuration variable: keep_files (default: ['.git']), based on this pull request: https://github.com/mojombo/jekyll/pull/556
removed puts
faster_lsi: Massively accelerate LSI performance.

Currently, Classifier::LSI rebuilds the index every time an entry is
added.  This runs into massive performance overheads on my website;
theoretically, disabling automatic index rebuilds, and explicitly
rebuilding the LSI index at the end of the LSI repopulation should
speed things up nicely.

As a side note, here, I use pandoc-ruby to provide a more featureful
Markdown transformer, so be mindful that the numbers I quote here have
artifically imposed I/O overheads.

With just the 76 posts I wrote this year (abysmal, I know), I come up
with the following figures:

    Without faster_lsi:
      jekyll --lsi  16.91s user 0.88s system 97% cpu 18.302 total
    With faster_lsi:
      jekyll --lsi  2.72s user 0.77s system 88% cpu 3.940 total

With 109 posts, we begin to see even better improvements:

    Without faster_lsi:
      jekyll --lsi  51.00s user 1.47s system 98% cpu 53.060 total
    With faster_lsi:
      jekyll --lsi  5.04s user 1.12s system 91% cpu 6.735 total

At this point, we begin to see I/O overheads being slower than LSI
when faster_lsi is active.  I call that fairly conclusive.  But wait,
there's more.  I have 273 posts lying around... I wonder what happens
if I feed them all in.  With faster_lsi, it was nice and clippy.
Without it, I simply gave up, and went and refilled my cup of tea.
And it was still going.

    Without faster_lsi:
      jekyll --lsi  1277.86s user 10.90s system 99% cpu 21:30.29 total
    With faster_lsi:
      jekyll --lsi  34.62s user 4.43s system 96% cpu 40.430 total

That is, in anyone's books, a major improvement.  Note, however, that
I don't know just how well this will perform with `jekyll --auto`
because I don't know how it does the LSI rebuilds.  I _think_ (but
please, don't commit me on this) that the LSI is rebuilt every time
Jekyll picks up a file change.

So, all up, the performance improvement is massive, and scales
depending on how many files you have.  At the last point, the
improvement is just on 3200%.

A more optimal solution would be to cache the LSI index and/or content
data somehow.  I'll leave that to when faster_lsi takes over ten
minutes to run.
Making sure errors don't halt the import.

Wrapped file operations in a begin/rescue block.
Convert slashes in titles to dashes when migrating from WordPress

When a post has a title that contains a slash, such as 'This is my cool
blog post part 1/2', convert the slash to a dash so that the post
filename is created correctly.

Fixes issue #680
use Array.join instead of Array.inject, add .svn to defaults
Add commander dependency
Add bin/jekyll2 and initial BuildCommand

The `BuildCommand` class is responsible for handling the building of the site.
It can also optionally watch for changes to files and regenerate the site if
needed.

The `Command` class holds any methods which are used by any command
implementation.
Add initial serve command

The `ServeCommand` will let you serve your site locally for development. You
can specify `--port`, `--host` and `--baseurl` options if you wish to change the
defaults.

Additionally the `BuildCommand` will be called before the processing of the
serve command, this makes sure that the site is actually built. This means you
are able to pass the `--watch` option to auto-regenerate your site, even while
serving it locally.
Update global options and command descriptions
Update loop position so trap handler is used
Add missing ] in self.watch string
Update Jekyll.configuration to convert symbol keys

Because Commander uses symbol keys in the options hash and I don't want to go
back backport every hash string key to symbols in Jekyll. :star:
Update the sym->str key conversion
Update to make the help command default
Rename Args to Options in command docs
Add TODOs for current switches
Add LSI option for build and serve commands