Pester.bat no longer enables strict mode.

This change was originally made to ensure that Pester's unit tests are run with strict mode enabled, so we would catch any bugs.  However, making this change in Pester.bat affects all users of Pester (or at least the ones who use the convenience batch file for integration.)

Pester's unit test scripts have since each been modified to enable Strict Mode at the beginning of each file, and we should no longer require this to be set in Pester.bat.  This way, users of Pester are not forced to write their test scripts in a way that is StrictMode-compatible.
Merge pull request #172 from dlwyatt/NoStrictModeByDefault

Pester.bat no longer enables strict mode.
Updated changelog for PR172.
Describe and Context fix

Fixture parameters to Describe was mistakenly marked as Mandatory in a recent commit.  Instead of that, its previous behavior was to be optional, but to throw a more user-friendly error message if it's not specified.

Added tests to make sure this doesn't happen again, and also applied the same logic / tests to the Context command.
Merge pull request #174 from dlwyatt/DescribeFix

Describe and Context fix
Changelog update for PR174
Errors reported from Describe and Context blocks

Quick update to make terminating errors that occur in a Describe or Context block cause a failed "test" to appear in the output.

Because we're just piggybacking onto the existing PesterState.AddTestResult and Write-PesterResult code, the output looks as though it came from an It statement, though the name is always "Error occurred in Context block" or "Error occurred in Describe block".  If this style of output is undesirable, a more extensive code update would be required.
Test failure for script file errors (syntax, etc)

This is along the same lines as the original commit in this branch, but addresses issue #91.

Also moved the calls to Add-SetupAndTeardown into the Try blocks of Describe and Context.