gitignore: ignore eggs, .pyo's and /build

This commit sets up .gitignore so that it properly ignores both
.pyo and .pyc files.

The egg path was updated so that it is prepended with a "/".

"/build" was added to the list of ignored paths since it is
customary for setuptools to use that directory for builds.

Signed-off-by: David Aguilar <davvid@gmail.com>

Author: davvid

.gitignore

@@ -1,2 +1,3 @@
-*.pyc
-lib/GitPython.egg-info
+*.py[co]
+/lib/GitPython.egg-info
+/build