Converted iOS powershell tasks to typescript

[SkyeHoefling]

Updated iOSBumpVersion and iOSBundleIdentifier from powershell to typescript, this PR fixes 1/2 of #4 . This is my first attempt at typescript so stuff isn't perfect but it is good enough to run the builds.

Build Agent Pre-Req This may become a problem, but I was unable to include the node module tsd. I added it globally for now until we can figure out a better way to do this. I mentioned this in the issue #4

Test Cases I published the tasks onto my local mac build agent and was able to run them successfully.

Publishing To properly publish these out to the marketplace run the following commands

1. navigate to tasks/iOSBumpVersion
   1. exec npm install to download node dependencies
   2. exec tsc to build js task
2. navigate to tasks/iOSBundleIdentifier
   1. exec npm install to download node dependencies
   2. exec tsc to build js task
3. exec tfx extension create --manifest-globs vss-extension.json
4. publish the vsix file to the marketplace

This PR only contains the iOS updates, I ran out of time and I am will be on vacation for the next 2 weeks. I wanted to get something submitted before leaving.

[SkyeHoefling]

@jamesmontemagno do you have a plan for this PR? Are we waiting for powershell core support? Do you want me to add android support?

I was able to publish this code to my personal VSTS marketplace account as a private extension and have it working in my build environment

[jamesmontemagno]

I can pull these in. I can try to do Android too today maybe :)

[SkyeHoefling]

If you run into issues I should be able to tackle it sometime next week, just let me know

[jamesmontemagno]

@ahoefling is iOSBundleIdentifier actually done? I only see:

// requires parameters if(!isNullOrUndefined(sourcePath)) { throw new Error("[!] Missing required input: sourcePath"); }

    console.log('Task done!');

[SkyeHoefling]

Looks like I never saved the file

I'm going to push changes back to this branch

[jamesmontemagno]

no worries i got it :)

[SkyeHoefling]

Oops, I'll delete my other PR