Allow hyphen for library name

I wrote an article [How to integrate PlatformIO Library Manager to Energia IDE](http://www.ikravets.com/computer-life/platformio/2014/10/07/integration-of-platformio-library-manager-to-arduino-and-energia-ides). But I have a problem with hyphen in library name. See error message:

<img src="http://f.cl.ly/items/1W243A2K2K2k3F2V1910/Screen%20Shot%202014-10-07%20at%2017.04.29.png">

Why hyphen is disallowed? Do you have any problems with it under OS?

P.S: I've started to fill database with [MSP430/Energia libraries](http://platformio.ikravets.com/#!/lib/search?query=msp430) recently. I hope that we will have more Energia's compatible libs in the future.

P.S.S: In this example I used ``MSP430-Energia-nRF24`` library: [library.json](https://github.com/spirilis/Enrf24/blob/master/library.json) and [Web](http://platformio.ikravets.com/#!/lib/show/MSP430-Energia-nRF24).
Merge pull request #485 from ivankravets/patch-1

Allow hyphen for library name