Parameters to bootstrap with "." not supported

@ravensorb commented on [Fri Jul 15 2016](https://github.com/cake-build/cake/issues/1069)
### What You Are Seeing?

Calling build.ps with a parameter that contains a "." is failing

Ex: .\build.ps1 -Target UnPublish -skipBuild=1 -versionToDelete="2.3.0-pre01"

Error:
Preparing to run build script...
Running build script...
More than one build script specified.
### What is Expected?

Parameter is passed to cake script
### What version of Cake are you using?

0.13.0
### Are you running on a 32 or 64 bit system?

64
### What environment are you running on? Windows? Linux? Mac?

Windows
### Are you running on a CI Server? If so, which one?
### How Did You Get This To Happen? (Steps to Reproduce)

Run the following command
- .\build.ps1 -Target UnPublish -skipBuild=1 -versionToDelete="2.3.0-pre01"
### Output Log

PS E:\Project> .\build.ps1 -Target UnPublish -skipBuild=1 -versionToDelete="2.3.0-pre01" -verbosity Diagnostic -debug
Preparing to run build script...
Running build script...
More than one build script specified.
Module directory does not exist.

Usage: Cake.exe [build-script] [-verbosity=value]
[-showdescription] [-dryrun] [..]

Example: Cake.exe
Example: Cake.exe build.cake -verbosity=quiet
Example: Cake.exe build.cake -showdescription

Options:
-verbosity=value Specifies the amount of information to be displayed.
(Quiet, Minimal, Normal, Verbose, Diagnostic)
-debug Performs a debug.
-showdescription Shows description about tasks.
-dryrun Performs a dry run.
-version Displays version information.
-help Displays usage information.
-mono Uses the Mono Compiler, rather than Roslyn script engine.
-experimental Uses the nightly builds of Roslyn script engine.

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@devlead commented on [Fri Jul 15 2016](https://github.com/cake-build/cake/issues/1069#issuecomment-232983030)

Does it work if you change to
`.\build.ps1 -Target UnPublish -Script .\build.cake -verbosity Diagnostic '-skipBuild=1 -versionToDelete="2.3.0-pre01" -debug'`

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@ravensorb commented on [Fri Jul 15 2016](https://github.com/cake-build/cake/issues/1069#issuecomment-232984059)

Yes that does seem to work

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@devlead commented on [Fri Jul 15 2016](https://github.com/cake-build/cake/issues/1069#issuecomment-232984772)

Excellent 👍

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@ravensorb commented on [Fri Jul 15 2016](https://github.com/cake-build/cake/issues/1069#issuecomment-232986672)

Hopefully that means its an easy fix :grinning:

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@Sebazzz commented on [Thu Aug 11 2016](https://github.com/cake-build/cake/issues/1069#issuecomment-238775171)

The default bootstrapper script is wrong and over complicated. It evals an expression, and if you format your command line parameters a certain way, the expression becomes invalid.

I've [added a pull request](https://github.com/cake-build/example/issues/27) to fix the bootstrapper script.