Pod search "+" raises an exception

### What did you do?

```shell
$ pod search +
```

### What did you expect to happen?

I'd find a list of all pod's like http://cocoapods.org/?q=name%3A%2B

### What happened instead?

See stack trace

### Stack

```
   CocoaPods : 0.29.0
        Ruby : ruby 2.0.0p247 (2013-06-27 revision 41674) [universal.x86_64-darwin13]
    RubyGems : 2.0.3
        Host : Mac OS X 10.9.1 (13B42)
       Xcode : 5.0.2 (5A3005)
Ruby lib dir : /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib
Repositories : master - https://github.com/CocoaPods/Specs.git @ 5921fb92652ebde992a2b820bceeae71ac463530
```

### Error

```
RegexpError - target of repeat operator is not specified: /+/i
/Users/kylef/gems/gems/cocoapods-core-0.29.0/lib/cocoapods-core/source.rb:211:in `search_by_name'
/Users/kylef/gems/gems/cocoapods-core-0.29.0/lib/cocoapods-core/source/aggregate.rb:123:in `block in search_by_name'
/Users/kylef/gems/gems/cocoapods-core-0.29.0/lib/cocoapods-core/source/aggregate.rb:122:in `each'
/Users/kylef/gems/gems/cocoapods-core-0.29.0/lib/cocoapods-core/source/aggregate.rb:122:in `search_by_name'
/Users/kylef/gems/gems/cocoapods-0.29.0/lib/cocoapods/sources_manager.rb:76:in `search_by_name'
/Users/kylef/gems/gems/cocoapods-0.29.0/lib/cocoapods/command/search.rb:63:in `local_search'
/Users/kylef/gems/gems/cocoapods-0.29.0/lib/cocoapods/command/search.rb:44:in `run'
/Users/kylef/gems/gems/claide-0.4.0/lib/claide/command.rb:213:in `run'
/Users/kylef/gems/gems/cocoapods-0.29.0/lib/cocoapods/command.rb:51:in `run'
/Users/kylef/gems/gems/cocoapods-0.29.0/bin/pod:24:in `<top (required)>'
/Users/kylef/gems/bin/pod:23:in `load'
/Users/kylef/gems/bin/pod:23:in `<main>'
```