Added ThumbnailService podspec

[alexgarbarev]

No description provided.

[squarefrog]

ThumbnailService/1.0.0/ThumbnailService.podspec [Full]
 -> ThumbnailService (1.0.0)
    - ERROR | Missing required attribute `homepage`.
    - WARN  | The summary should be a short version of `description` (max 140 characters).
    - NOTE  | [xcodebuild]  ThumbnailService/ThumbnailService/ThumbnailService/Operations/TSRequestedOperation.m:116:26: warning: implicit conversion from enumeration type 'TSRequestQueuePriority' (aka 'enum TSRequestQueuePriority') to different enumeration type 'NSOperationQueuePriority' (aka 'enum NSOperationQueuePriority') [-Wenum-conversion]
    - NOTE  | [iOS] [xcodebuild]  ThumbnailService/ThumbnailService/ThumbnailService/Sources/TSSourceImage.m:29:55: warning: values of type 'NSUInteger' should not be used as format arguments; add an explicit cast to 'unsigned long' instead [-Wformat]
    - NOTE  | [iOS] [xcodebuild]  ThumbnailService/ThumbnailService/ThumbnailService/Sources/TSSourceVideo.m:31:58: warning: values of type 'NSUInteger' should not be used as format arguments; add an explicit cast to 'unsigned long' instead [-Wformat]
    - WARN  | [iOS] Unable to find a license file
 -> The spec cannot be accepted.

You need to set the homepage, and license properties. Also summary can be a maximum of 140 characters.

[alexgarbarev]

• added homepage attribute
• code pass "-Wextra -Werror -pedantic" warnings
• added license file
• change summary
• added description