storages: memory object

[mcuadros]

New scaffolding for different storage methods also core.RawObject has be move to memory.Object.

/cc @JoshuaSjoding

[codecov-io]

Current coverage is 60.10%

Merging #28 into master will increase coverage by +1.59% as of 5b4cd55

@@            master    #28   diff @@
=====================================
  Files           24     26     +2
  Stmts         1567   1584    +17
  Branches       200    205     +5
  Methods          0      0       
=====================================
+ Hit            917    952    +35
- Partial         93     97     +4
+ Missed         557    535    -22

Review entire Coverage Diff as of 5b4cd55

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[JoshuaSjoding]

@mcuadros This looks great to me. The only thing I propose changing is to rename the directory from storages to storage. Whether or not "storages" is a legitimate plural in English is probably a matter of some debate, but simply using "storage" here sounds more natural to me.

This changeset sets us up nicely for a file-based storage implementation.