Sb/build local cache

[SBFRF]

this ties to Issue #5. Need to build a local cache when downloading data. inital approach will be to build a local copy of the TDS server. This will require downloading netCDF files and creating a folder structure to mimic that of the TDS server (at a specified userDefined location, then with each new querey, grabbing those files, and populating the folder structure. if some variable (say pullFromLocalCache is marked True on initialization, then the qurery can then just update the TDS file path to the local path directory (instead of the URL), and output should otherwise remain the same

• At some point, logic will have to be rolled in to check the modified data and update the local copy. This will not be included in this PR.
• it will build off of the server check

@thesser1 what do you think about this logic and approach?

[SBFRF]

@thesser1 let me know what you think, this is a simple (read fast) implementation for a single file. I'm not sure how we expand it out. but maybe something to add to the road map