Update 9. LINQ.md

Added a subchapter describing the differences between First(), FirstOrDefault(), Single() and SingleOrDefault(). Since these functions are frequently needed, it is good to know when to use each one.
fix spelling
Added week00 folder with git and github info

Added week00 folder with basic description and links to resources about
git and github
Update Skil 1 - nuget.md
Update Python_environment_install_OSX.md

Minor url spelling error fix.
Merge pull request #16 from arnorb/patch-2

Update Python_environment_install_OSX.md
Update Python_environment_install_OSX.md

Fix spelling, grammar and minor instructions.
Merge pull request #17 from arnorb/patch-3

Update Python_environment_install_OSX.md
Update 1. Web Services.md

Fix spelling.
Merge pull request #11 from gudmundurste12/patch-1

Update 9. LINQ.md
Merge pull request #13 from sse87/master

Added week00 folder with git and github info
Merge pull request #18 from arnorb/patch-2

Update 1. Web Services.md
Merge pull request #12 from arnorb/patch-1

fix spelling
Adding the first part of Python labs
Merge remote-tracking branch 'upstream/master'