setup: being careful and removing the Py3.2 support
Added the license
Renaming ast_pe to peval

Reasons:
1. Hiding the implementation detail (AST), in case it changes later. User doesn’t care if it’s AST or not, as long as it works.
2. Now it contains more information about the actual purpose (peval vs pe).
3. Package names with underscores are usually discouraged.
4. The original author can still use ast_pe if he decides to develop his version further.