Change base license to BSD 3-clause

Something I mentioned to @martinavila some time ago was that for open source projects/modules released under our individual developer names (but containing TerraEclipse attribution), we should be using the BSD 3-clause license, which is a bit more protective than the MIT license in that it also contains a clause restricting certain uses of the company's name without specific permission.

For full-blown TerraEclipse projects/modules, we should use the Apache 2 license.