Add cr2 as image

Fix some issues indicated by clippy

The last PR was meant to remove the duplicate bitflags, but I think I messed it up and another one crept in.

Use official vagrant jessie64

Update dependencies

Exit with a non-zero status on error

Update git2 to 0.6.4

With `ls` from Debian coreutils 8.26-2

```
ls /bad/path
echo $? # => 2
```

Reproduced same behaviour with exa

Fix https://github.com/ogham/exa/issues/135

* Also remove bitflags as it isn't used.
* Don't update ansi_term as ANSIString is no longer Clone.

This adds an option (always on at the moment) to use a colour scale of green to yellow to orange for the file size field instead of always green. See #65.

This makes the Colours value pick a colour based on the size of the file, instead of necessarily having them all green. (They are all green for now, though.)

See #97 and recently #130 too.

This allows the user to pass in options such as "--ignore '*.pyc'" to not list any files ending in '.pyc' in the output. It uses the Rust glob crate and currently does a simple split on pipe, without any escaping, so it’s not really *complete*, but is at least something.

This has to be done for when ignore patterns get introduced and have to be stored in a Vec.

Fixes #123. The code assumes that every File that has its link_target() method called would first have been checked to make sure it’s actually a link first. Unfortunately it also assumed that the only thing that can go wrong while following a link is if the file wasn’t a link, meaning it crashes when given a link it doesn’t have permission to follow.

This makes the file_target() method able to return either a file or path for displaying, as before, but also an IO error for when things go wrong.

Fixes #129

This changes the way that views are used to display the actual lists of files. It used to pass empty vectors to the view methods, which most of the time would not print anything because there are no files to list — except when there’s a header row which gets printed for no files.

By not calling the view method at all when there’s nothing to print, exa won’t ever print extra things in the view unless it needs to for a file.

This fixes #106 “Don’t print the header if the result set is empty”

See the README section for more details. Basically, with this way, we can store a bunch of existing valid exa outputs, change a VM's environment to match our values, then check that exa still works by comparing outputs.