bug fix when error bar is zero

- fixed a bug that an exception is thrown when error bar is zero.
  - due to a numerical error, sqrt of a negative value is sometimes calculated.
Merge pull request #198 from crest-cassia/bugfix_calc_error_bar

bug fix when error bar is zero
implement log scale plot
enable to set log scale on explore
add test for log scale
a bug is fix on javascript array assignment operation
Merge pull request #200 from crest-cassia/hot_fix_javascript_on_chome

a bug is fix on javascript array assignment operation
Merge pull request #199 from crest-cassia/plots_with_log_scale

implement log scale plot
a typo is fixed
copy codes form figures_on_scatter_plot
copy spec form figures_on_scatter_plot
adjust figure size [point, middle, large]
refactoring
do not launch worker when READ_ONLY mode is enabled
set const when read_only mode is enabled
enable to put figures with log scale
disable EDIT actions

- disable new, create, edit, update, destroy actions
add description for READ_ONLY mode
Merge pull request #203 from crest-cassia/read_only_mode

Read only mode
Merge branch 'Development' of github.com:crest-cassia/oacis into figures_displayed_on_scatter_plot