redstore 0.5.4 fails when using sqlite storage

I'm getting the following error using `redstore` with sqlite storage:

```
experiments/redstore$ redstore -n
[INFO]    Tue May  7 17:02:25 2013  Storage name: redstore
[INFO]    Tue May  7 17:02:25 2013  Storage type: hashes
[INFO]    Tue May  7 17:02:25 2013  Storage options: write='yes', hash-type='memory', new='yes', contexts='yes'
[INFO]    Tue May  7 17:02:25 2013  Starting HTTP server on port 8080
^C[INFO]    Tue May  7 17:02:28 2013  Got interupt signal.
experiments/redstore$ redstore -n -s sqlite
[INFO]    Tue May  7 17:02:36 2013  Storage name: redstore
[INFO]    Tue May  7 17:02:36 2013  Storage type: sqlite
[INFO]    Tue May  7 17:02:36 2013  Storage options: write='yes', new='yes', contexts='yes'
[ERROR]   Tue May  7 17:02:36 2013  storage 'redstore' not found
[ERROR]   Tue May  7 17:02:36 2013  Failed to open sqlite storage 'redstore'
[FATAL]   Tue May  7 17:02:36 2013  Failed to open librdf storage.
```

A closed issue at njh/redstore#41 suggests that identical symptoms on Ubuntu were caused by a lack of -dev packages, but @njh doesn't list which those packages are (and in any case, my knowledge of compiling isn't good enough to know how to get homebrew to work with them)

```
$ brew --config
HOMEBREW_VERSION: 0.9.4
ORIGIN: https://github.com/mxcl/homebrew
HEAD: 29e4f5f54e77f5f63589b3a73b518948d67ae08d
HOMEBREW_PREFIX: /usr/local
HOMEBREW_CELLAR: /usr/local/Cellar
CPU: 8-core 64-bit ivybridge
OS X: 10.7.5-x86_64
Xcode: 4.6
CLT: 4.5.0.0.1.1249367152
GCC-4.2: build 5666
LLVM-GCC: build 2336
Clang: 4.1 build 421
X11: 2.6.5 => /usr/X11
System Ruby: 1.8.7-358
Perl: /usr/bin/perl
Python: /usr/bin/python
Ruby: /Users/garetha/.rvm/rubies/ruby-1.9.3-p286/bin/ruby
$ brew doctor
Warning: Your Xcode (4.6) is outdated
Please install Xcode 4.6.2.
$
```