Finch web client + new batch update operations

This release migrates from HTTPoison to Finch and includes new batch update operations.
They are not heavily tested so use at your own risk:

• GSS.Spreadsheet.set_basic_filter(pid, %{row_from: 0, row_to: 5, col_from: 1, col_to: 10}, %{col_idx: 2, condition_type: "TEXT_CONTAINS", user_entered_value: "test"})
• GSS.Spreadsheet.set_basic_filter(pid, %{row_from: nil, row_to: nil, col_from: nil, col_to: nil}, %{})
• GSS.Spreadsheet.clear_basic_filter(pid)
• GSS.Spreadsheet.freeze_header(pid, %{dim: :row, n_freeze: 1})
• GSS.Spreadsheet.freeze_header(pid, %{dim: :col, n_freeze: 2})
• GSS.Spreadsheet.update_col_width(pid, %{col_idx: 1, col_width: 200})
• GSS.Spreadsheet.add_number_format(pid, %{row_from: 0, row_to: nil, col_from: 3, col_to: 4}, %{type: "NUMBER", pattern: "#0.0%"})
• GSS.Spreadsheet.update_col_wrap(pid, %{row_from: 0, row_to: nil, col_from: 5, col_to: 7}, %{wrap_strategy: "clip"})
• GSS.Spreadsheet.set_font(pid, %{row_from: nil, row_to: nil, col_from: nil, col_to: nil}, %{font_family: "Source Code Pro"})
• GSS.Spreadsheet.add_conditional_format(pid, %{row_from: nil, row_to: nil, col_from: nil, col_to: nil}, %{formula: "=$E1=\"TEST\"", color_map: %{red: 1, green: 0.8, blue: 0.8}})
• GSS.Spreadsheet.update_border(pid, %{row_from: 0, row_to: 10, col_from: 2, col_to: 5}, %{top: %{red: 1, style: "dashed"}, bottom: %{green: 1, blue: 0.7}, left: %{blue: 0.8, alpha: 0.75}})

Updated to goth 1.3-rc

Merge pull request #47 from MonsieurV/master

Migrate to Goth 1.3+

Updated dyalixir and logger_file_backend

v0.2.2

Updated utility libs

Adopted Elixir 1.12, updated all deps

v0.2.0

Updated to Elixir 1.12, bumped deps

Bumped GenStage and Httpoison deps.

Memory leak fix

Allowed nils for row appends

v0.1.15

Bumped readme version

Added support for appending of multiple rows in single request

v0.1.14

Hotfix for high row append indexes

Bumped versions of core dependencies

v0.1.11

Fixed doc generation

Various minor improvements, batch of ranges for read_rows, new sheets method.

v0.1.10-beta

Enabled batch of ranges by default on read_rows

Improved cell range management for composite columns

Should fix issues with some complex column names like "AZ", "ZZ1" etc