fixed check for dependencies in constant template

Firstly, thank you for this plugin =)
I found strange behavior when "deps" option is not defined in json file.
Example:
```
{
    "name": "exmpl",
    "constants": {
            "protocol": "http",
            "hostname": "localhost",
            "port": "80"
}
}
```
compiles to
```
angular.module("exmpl", [])

.constant(
	"protocol": "http",
	"hostname": "localhost",
	"port": "80"
)
;
```
Using this code, i get same error http://stackoverflow.com/questions/16006313/unknown-provider-resourceprovider-resource-with-angularjs
I think, if "deps" option is not defined, angular module should not include empty dependencies array.