Implement Default ceil Functionality for Base Tensor Type

[iamtrask]

User Story A: As a Data Scientist using Syft's Base Tensor type, we want to implement a default method for computing operations on a Tensor of arbitrary type. For this ticket to be complete, ceil() should return a new tensor and ceil_() should perform the operation inline. For a reference on the operation this performs check out PyTorch's documentation.

Acceptance Criteria:

• If the Base Tensor type's attribute "encrypted" is set to True, it should return a NotImplemented error.
• a unit test demonstrating the correct operation on the Base Tensor type implemented over int and float Tensors.
• inline documentation in the python code. For inspiration on inline documentation, please check out PyTorch's documentation for this operator.

[EdwardDixon]

Addressed with this pull request

[siarez]

Should this be closed? @iamtrask

[iamtrask]

Yes! Thank you.