Add EC2 instance pricing list page

@xiaohua-guan

Thank you for the patch. It looks great. Here is the screenshot for us-east-1 and ap-northeast-1.

us-east-1

ap-northeast-1

I want to request the following minor cosmetic changes:

1. Add one white space in between e.g. Hourly and ($) on the header. Therefore it will become Hourly ($), Daily ($), Monthly ($), 1 Year ($), 3 Year ($).
2. The each header element should be aligned to be centered (not left-justified)
3. At On-demand Hourly ($), the floating number digits should be four (e.g. 1.2345 or 4.5678 (rounded value) for micro instance types.
4. At On-demand Daily ($) and On-demand Monthly ($), the floating number digits should be two (e.g. 1.23 or 4.56 (rounded value)
5. At On-demand Yearly ($), the number can be an integer (rounded value) because it is easy to compare to RI 1 Year ($).
6. Add an action link for Instance Type Prices into Server Template's Add / Edit page.

@xiaohua-guan

Thank you for your update. It looks good to me, and I would like to have the following further request to make it perfect:

1. Add vertical-align: middle; to all table elements (headers and rows)
2. Change the one year period as follows:
   

   ...
           const ONE_YEAR = 365.25
   ...
           'on_demand_monthly' => floatval($hourly_rate) * 24 * ONE_YEAR / 12,
           'on_demand_yearly'  => floatval($hourly_rate) * 24 * ONE_YEAR,
   

@baldwinlouie

What do you think?

@xiaohua-guan,

Thank you for the update patch. It looks perfect to me but sorry, can you "Add an action link for Instance Type Prices into Server Template's Add / Edit page." for a new browser window?

@yas and @xiaohua-guan, Code looks good to me.

@xiaohua-guan

Great, thank you for the update！ I'll merge the patch and close the issue as Fixed. Thank you for your efforts.