ARROW-103: Add files to gitignore

Patches [ARROW-103](https://issues.apache.org/jira/browse/ARROW-103), though perhaps it would make sense to leave that issue open to cover any future .gitignore-related pull requests.

Author: Dan Robinson <danrobinson010@gmail.com>

Closes #62 from danrobinson/ARROW-103 and squashes the following commits:

7c1c7d8 [Dan Robinson] ARROW-103: Added '*-build' to cpp/.gitignore
633bacf [Dan Robinson] ARROW-103: Added '.cache' to python/.gitignore
59f58ba [Dan Robinson] ARROW-103: Add '*.dylib to python/.gitignore'
52572ab [Dan Robinson] ARROW-103: Add 'dev-build/' to cpp/.gitignore

cpp/.gitignore

@@ -5,6 +5,7 @@ CTestTestfile.cmake
 Makefile
 cmake_install.cmake
 build/
+*-build/
 Testing/
 
 #########################################

python/.gitignore

@@ -18,6 +18,7 @@ Testing/
 *.o
 *.py[ocd]
 *.so
+*.dylib
 .build_cache_dir
 MANIFEST
 
@@ -35,6 +36,8 @@ dist
 # coverage
 .coverage
 coverage.xml
+# cache
+.cache
 
 # benchmark working dir
 .asv