pep8 changes

## PEP 8
have look in the dosage code for style errors of PEP 8 -- Style Guide for Python Code http://legacy.python.org/dev/peps/pep-0008/
I have check die code with the pep8 tool. https://pypi.python.org/pypi/pep8
```
$ pep8 stage_build_mac.py 
stage_build_mac.py:36:80: E501 line too long (117 characters)
stage_build_mac.py:38:80: E501 line too long (87 characters)
stage_build_mac.py:47:1: E302 expected 2 blank lines, found 1
stage_build_mac.py:51:15: E701 multiple statements on one line (colon)
stage_build_mac.py:54:19: E701 multiple statements on one line (colon)
stage_build_mac.py:57:19: E701 multiple statements on one line (colon)
stage_build_mac.py:62:19: E701 multiple statements on one line (colon)
stage_build_mac.py:65:19: E701 multiple statements on one line (colon)
stage_build_mac.py:68:15: E701 multiple statements on one line (colon)
stage_build_mac.py:73:15: E701 multiple statements on one line (colon)
stage_build_mac.py:74:48: E231 missing whitespace after ','
stage_build_mac.py:76:15: E701 multiple statements on one line (colon)
stage_build_mac.py:76:50: E225 missing whitespace around operator
stage_build_mac.py:76:59: E225 missing whitespace around operator
stage_build_mac.py:77:35: E225 missing whitespace around operator
stage_build_mac.py:78:19: E701 multiple statements on one line (colon)
stage_build_mac.py:80:15: E701 multiple statements on one line (colon)
stage_build_mac.py:82:19: E701 multiple statements on one line (colon)
stage_build_mac.py:84:1: E302 expected 2 blank lines, found 1
stage_build_mac.py:100:1: E302 expected 2 blank lines, found 1
stage_build_mac.py:101:20: E225 missing whitespace around operator
stage_build_mac.py:102:20: E225 missing whitespace around operator
stage_build_mac.py:104:1: E302 expected 2 blank lines, found 1
stage_build_mac.py:112:80: E501 line too long (116 characters)
stage_build_mac.py:118:9: E303 too many blank lines (2)
stage_build_mac.py:119:31: E231 missing whitespace after ','
stage_build_mac.py:121:31: E231 missing whitespace after ','
stage_build_mac.py:125:31: E231 missing whitespace after ','
stage_build_mac.py:127:31: E231 missing whitespace after ','
stage_build_mac.py:144:21: W292 no newline at end of file
```