Add package.json

Add `package.json` file (as requested at https://github.com/interconnectit/Search-Replace-DB/issues/49) in order that this script can be utilised in 3rd party node modules.

For an example of how and why this might be required see 

https://github.com/getdave/grunt-deployments/tree/feature/advanced-search-replace

which specifiies the Search-Replace-DB script as a dependency.

Bumped version number as requested.