ACHE UI interface

DONE: Start and stop crawler from UI - crawl page pressing the play/stop buttons

To reproduce:
- Get the focused_crawler and compile it:

```bash
$ git clone git@github.com:ViDA-NYU/memexcrawler.git
$ cd memexcrawler/focused_crawler
$ ./script/compile_crawler.sh
```
- Set the variable CRAWLER_PATH in config.py to wherever you directory you save it

```
CRAWLER_PATH = '/Users/cdoig/work/memexcrawler/focused_crawler'
```

I'll add automated setup and better README and docs, ASAP.

I had to restart migrations folder. A sample app.db is available on Google Drive.